Create a custom folder in qmk_firmware/keyboards/planck/keymaps/YOUR_KEYMAP or modify the files in the "brandon" folder

config.h

#ifndef CONFIG_USER_H
#define CONFIG_USER_H

#include "../../config.h"

/* ws2812 RGB LED */
#define RGB_DI_PIN B2     // Don't modify this
#define RGBLIGHT_TIMER
#define RGBLED_NUM 10     // Number of LEDs
#define RGBLIGHT_HUE_STEP 10  // You could modify these
#define RGBLIGHT_SAT_STEP 17  // if you would like finer/coarser
#define RGBLIGHT_VAL_STEP 17  // control.

#endif

keymap.c

// This is the canonical layout file for the Quantum project. If you want to add another keyboard,
// this is the style you want to emulate.

#include "planck.h"
#include "action_layer.h"
#ifdef BACKLIGHT_ENABLE
  #include "backlight.h"
#endif
#include "eeconfig.h"

extern keymap_config_t keymap_config;

// Each layer gets a name for readability, which is then used in the keymap matrix below.
// The underscores don't mean anything - you can have a layer called STUFF or any other name.
// Layer names don't all need to be of the same length, obviously, and you can also skip them
// entirely and just use numbers.
#define _QWERTY 0
#define _WORKMAN 2
#define _LOWER 3
#define _RAISE 4
#define _ADJUST 16

enum planck_keycodes {
  QWERTY = SAFE_RANGE,
  WORKMAN,
  ESCTRL = MT(KC_RCTL, KC_ESC),
  LOWER = LT(_LOWER, KC_BSPC),
  RAISE = LT(_RAISE, KC_ENT),
  ADJUST,
  BACKLIT
};

// Fillers to make layering more clear
#define _______ KC_TRNS
#define XXXXXXX KC_NO

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {

/* Qwerty
 * ,-----------------------------------------------------------------------------------.
 * | Tab  |   Q  |   W  |   E  |   R  |   T  |   Y  |   U  |   I  |   O  |   P  | Bksp |
 * |------+------+------+------+------+-------------+------+------+------+------+------|
 * | Esc  |   A  |   S  |   D  |   F  |   G  |   H  |   J  |   K  |   L  |   ;  |  "   |
 * |------+------+------+------+------+------|------+------+------+------+------+------|
 * | Shift|   Z  |   X  |   C  |   V  |   B  |   N  |   M  |   ,  |   .  |   /  |Enter |
 * |------+------+------+------+------+------+------+------+------+------+------+------|
 * | Brite| Ctrl | Alt  | GUI  |Lower |    Space    |Raise | Left | Down |  Up  |Right |
 * `-----------------------------------------------------------------------------------'
 */
[_QWERTY] = {
  {KC_TAB,  KC_Q,    KC_W,    KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_BSPC},
  {ESCTRL,  KC_A,    KC_S,    KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT},
  {KC_LSFT, KC_Z,    KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH, KC_RSFT },
  {ADJUST, KC_LCTL, KC_LALT, KC_LGUI, LOWER,   KC_SPC,  KC_SPC,  RAISE,   KC_LEFT, KC_DOWN, KC_UP,   KC_RGHT}
},
/* Workman
 * ,-----------------------------------------------------------------------------------.
 * | Tab  |   Q  |   D  |   R  |   W  |   B  |   J  |   F  |   U  |   P  |   ;  | Bksp |
 * |------+------+------+------+------+-------------+------+------+------+------+------|
 * | Esc  |   A  |   S  |   H  |   T  |   G  |   Y  |   N  |   E  |   O  |   I  |  "   |
 * |------+------+------+------+------+------|------+------+------+------+------+------|
 * | Shift|   Z  |   X  |   M  |   C  |   V  |   K  |   L  |   ,  |   .  |   /  |Enter |
 * |------+------+------+------+------+------+------+------+------+------+------+------|
 * |Adjust| Ctrl | Alt  | GUI  |Lower |Space |Space |Raise | Left | Down |  Up  |Right |
 * `-----------------------------------------------------------------------------------'
 */
[_WORKMAN] = {
  {KC_TAB,  KC_Q,    KC_D,    KC_R,    KC_W,    KC_B,    KC_J,    KC_F,    KC_U,    KC_P,    KC_SCLN, KC_BSPC},
  {ESCTRL,  KC_A,    KC_S,    KC_H,    KC_T,    KC_G,    KC_Y,    KC_N,    KC_E,    KC_O,    KC_I,    KC_QUOT},
  {KC_LSFT, KC_Z,    KC_X,    KC_M,    KC_C,    KC_V,    KC_K,    KC_L,    KC_COMM, KC_DOT,  KC_SLSH, KC_RSFT},
  {ADJUST,  KC_LCTL, KC_LALT, KC_LGUI, LOWER,   KC_SPC,  KC_SPC,  RAISE,   KC_LEFT, KC_DOWN, KC_UP,   KC_RGHT}
},
/* Lower
 * ,-----------------------------------------------------------------------------------.
 * |   ~  |   !  |   @  |   #  |   $  |   %  |   ^  |   &  |   *  |   (  |   )  | Bksp |
 * |------+------+------+------+------+-------------+------+------+------+------+------|
 * | Del  |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |   _  |   +  |   {  |   }  |  |   |
 * |------+------+------+------+------+------|------+------+------+------+------+------|
 * |      |  F7  |  F8  |  F9  |  F10 |  F11 |  F12 |ISO ~ |ISO | |      |      |Enter |
 * |------+------+------+------+------+------+------+------+------+------+------+------|
 * |      |      |      |      |      |             |      | Next | Vol- | Vol+ | Play |
 * `-----------------------------------------------------------------------------------'
 */
[_LOWER] = {
  {KC_TILD, KC_EXLM, KC_AT,   KC_HASH, KC_DLR,  KC_PERC, KC_CIRC, KC_AMPR, KC_ASTR, KC_LPRN, KC_RPRN, KC_BSPC},
  {KC_DEL,  KC_F1,   KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   KC_UNDS, KC_PLUS, KC_LCBR, KC_RCBR, KC_PIPE},
  {_______, KC_F7,   KC_F8,   KC_F9,   KC_F10,  KC_F11,  KC_F12,S(KC_NUHS),S(KC_NUBS),_______, _______, _______},
  {_______, _______, _______, _______, _______, _______, _______, _______, KC_MNXT, KC_VOLD, KC_VOLU, KC_MPLY}
},

/* Raise
 * ,-----------------------------------------------------------------------------------.
 * |   `  |   1  |   2  |   3  |   4  |   5  |   6  |   7  |   8  |   9  |   0  | Bksp |
 * |------+------+------+------+------+-------------+------+------+------+------+------|
 * | Del  |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |   -  |   =  |   [  |   ]  |  \   |
 * |------+------+------+------+------+------|------+------+------+------+------+------|
 * |      |  F7  |  F8  |  F9  |  F10 |  F11 |  F12 |ISO # |ISO / |      |      |Enter |
 * |------+------+------+------+------+------+------+------+------+------+------+------|
 * |      |      |      |      |      |             |      | Next | Vol- | Vol+ | Play |
 * `-----------------------------------------------------------------------------------'
 */
[_RAISE] = {
  {KC_GRV,  KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,    KC_8,    KC_9,    KC_0,    KC_BSPC},
  {KC_DEL,  KC_F1,   KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   KC_MINS, KC_EQL,  KC_LBRC, KC_RBRC, KC_BSLS},
  {_______, KC_F7,   KC_F8,   KC_F9,   KC_F10,  KC_F11,  KC_F12,  KC_NUHS, KC_NUBS, _______, _______, _______},
  {_______, _______, _______, _______, _______, _______, _______, _______, KC_MNXT, KC_VOLD, KC_VOLU, KC_MPLY}
},

/* Adjust (Lower + Raise)
 * ,-----------------------------------------------------------------------------------.
 * |      | Reset|      |      |      |      |      |      |      |      |      |  Del |
 * |------+------+------+------+------+-------------+------+------+------+------+------|
 * |      |      |      |Aud on|Audoff|AGnorm|AGswap|Qwerty|Colemk|Dvorak|Plover|      |
 * |------+------+------+------+------+------|------+------+------+------+------+------|
 * |      |Voice-|Voice+|Mus on|Musoff|MIDIon|MIDIof|      |      |      |      |      |
 * |------+------+------+------+------+------+------+------+------+------+------+------|
 * |      |      |      |      |      |             |      |      |      |      |      |
 * `-----------------------------------------------------------------------------------'
 */
[_ADJUST] = {
  {_______, RESET,   _______, _______, _______, _______, _______, _______, _______, _______, _______, KC_DEL},
  {_______, _______, _______, _______, _______, AG_NORM, AG_SWAP, QWERTY,  WORKMAN, _______, _______,  _______},
  {_______, RGB_TOG, RGB_MOD, RGB_HUI, RGB_HUD, RGB_SAI, RGB_SAD, RGB_VAI, RGB_VAD, _______, _______, _______},
  {_______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______}
}


};

void persistant_default_layer_set(uint16_t default_layer) {
  eeconfig_update_default_layer(default_layer);
  default_layer_set(default_layer);
}

bool process_record_user(uint16_t keycode, keyrecord_t *record) {
  switch (keycode) {
      case QWERTY:
        if (record->event.pressed) {
          #ifdef AUDIO_ENABLE
            PLAY_NOTE_ARRAY(tone_qwerty, false, 0);
          #endif
          persistant_default_layer_set(1UL<<_QWERTY);
        }
        return false;
        break;
    case LOWER:
      if (record->event.pressed) {
        layer_on(_LOWER);
        update_tri_layer(_LOWER, _RAISE, _ADJUST);
      } else {
        layer_off(_LOWER);
        update_tri_layer(_LOWER, _RAISE, _ADJUST);
      }
      // return false;
      break;
    case RAISE:
      if (record->event.pressed) {
        layer_on(_RAISE);
        update_tri_layer(_LOWER, _RAISE, _ADJUST);
      } else {
        layer_off(_RAISE);
        update_tri_layer(_LOWER, _RAISE, _ADJUST);
      }
      // return false;
      break;
    case WORKMAN:
      if (record->event.pressed) {
        #ifdef AUDIO_ENABLE
          PLAY_NOTE_ARRAY(tone_dvorak, false, 0);
        #endif
        persistant_default_layer_set(1UL<<_WORKMAN);
        }
        return false;
        break;
    case BACKLIT:
      if (record->event.pressed) {
        register_code(KC_RSFT);
        #ifdef BACKLIGHT_ENABLE
          backlight_step();
        #endif
      } else {
        unregister_code(KC_RSFT);
      }
      return false;
      break;
    case ADJUST:
        if (record->event.pressed) {
          layer_on(_ADJUST);
        } else {
          layer_off(_ADJUST);
        }
        return false;
        break;
  }
  return true;
}

void matrix_init_user(void) {
    #ifdef AUDIO_ENABLE
        startup_user();
    #endif
}

Makefile

# Build Options
#   change to "no" to disable the options, or define them in the Makefile in
#   the appropriate keymap folder that will get included automatically
#
BOOTMAGIC_ENABLE = no       # Virtual DIP switch configuration(+1000)
MOUSEKEY_ENABLE = yes       # Mouse keys(+4700)
EXTRAKEY_ENABLE = yes       # Audio control and System control(+450)
CONSOLE_ENABLE = no         # Console for debug(+400)
COMMAND_ENABLE = yes        # Commands for debug and configuration
NKRO_ENABLE = yes            # Nkey Rollover - if this doesn't work, see here: https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work
BACKLIGHT_ENABLE = yes      # Enable keyboard backlight functionality
MIDI_ENABLE = no            # MIDI controls
AUDIO_ENABLE = no           # Audio output on port C6 DO NOT ENABLE IF USING RGBLIGHT
UNICODE_ENABLE = no         # Unicode
BLUETOOTH_ENABLE = no       # Enable Bluetooth with the Adafruit EZ-Key HID
RGBLIGHT_ENABLE = yes        # Enable WS2812 RGB underlight.  Do not enable this with audio at the same time.

# Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
SLEEP_LED_ENABLE = no    # Breathing sleep LED during USB suspend

ifndef QUANTUM_DIR
	include ../../../../Makefile
endif