Simple two Windows app for Pebble.

twowindows.c

#include <pebble.h>

static Window *window_1, *window_2;
static TextLayer *text_layer_1, *text_layer_2;

/********************************* Window 2 stuff ***********************************/

static void window_2_load(Window *window) {
  text_layer_2 = text_layer_create(GRect(0, 0, 144, 168));
  text_layer_set_text(text_layer_2, "Window 2. \nBACK for Window 1.");
  text_layer_set_text_alignment(text_layer_2, GTextAlignmentLeft);
  text_layer_set_font(text_layer_2, fonts_get_system_font(FONT_KEY_GOTHIC_24_BOLD));
  layer_add_child(window_get_root_layer(window), text_layer_get_layer(text_layer_2));
}

static void window_2_unload(Window *window) {
  text_layer_destroy(text_layer_2);

  //Careful with this
  window_destroy(window_2);
}

/********************************* Window 1 stuff ***********************************/

static void select_click_handler(ClickRecognizerRef recognizer, void *context) {
  //Load window 2
  window_2 = window_create();
  window_set_window_handlers(window_2, (WindowHandlers) {
    .load = window_2_load,
    .unload = window_2_unload,
  });
  window_stack_push(window_2, true);    //That's all there is too it!
}

static void click_config_provider(void *context) {
  window_single_click_subscribe(BUTTON_ID_SELECT, select_click_handler);
}

static void window_1_load(Window *window) {
  text_layer_1 = text_layer_create(GRect(0, 0, 144, 168));
  text_layer_set_text(text_layer_1, "Window 1. \nSELECT for Window 2.");
  text_layer_set_text_alignment(text_layer_1, GTextAlignmentLeft);
  text_layer_set_font(text_layer_1, fonts_get_system_font(FONT_KEY_GOTHIC_24_BOLD));
  layer_add_child(window_get_root_layer(window), text_layer_get_layer(text_layer_1));
}

static void window_1_unload(Window *window) {
  text_layer_destroy(text_layer_1);
  window_destroy(window_1);
}

/******************************** Main app stuff ************************************/

static void init(void) {
  //Start with window 1
  window_1 = window_create();
  window_set_click_config_provider(window_1, click_config_provider);
  window_set_window_handlers(window_1, (WindowHandlers) {
    .load = window_1_load,
    .unload = window_1_unload,
  });
  window_stack_push(window_1, true);
}

static void deinit(void) {
  
}

int main(void) {
  init();
  app_event_loop();
  deinit();
}