Register WordPress sidebars demo

functions.php

<?php

/**
 * Intitiate sidebars
 *
 * @link https://developer.wordpress.org/reference/functions/register_sidebar/
 */
function mytheme_widgets_init() {
	// Sidebar.
	register_sidebar(
		array(
			'name' => esc_html__( 'Sidebar Main', 'mytheme' ),
			'id' => 'sidebar-1',
			'description' => esc_html__( 'Widgets that display on the side of your website', 'mytheme' ),
			'before_widget' => '<section id="%1$s" class="widget %2$s"><div class="widget-wrap">',
			'after_widget' => '</div></section>',
			'before_title' => '<h2 class="widget-title">',
			'after_title' => '</h2>',
		)
	);
}
add_action( 'widgets_init', 'mytheme_widgets_init' );

sidebar.php

<?php
/**
 * Sidebar Template
 *
 * Display the sidebar widgets. Will not output anything if there's no widgets
 * assigned to specified sidebar.
 *
 * @link https://developer.wordpress.org/themes/template-files-section/partial-and-miscellaneous-template-files/#sidebar-php
 */

if ( is_active_sidebar( 'sidebar-1' ) ) {
?>

<!-- Sidebar Main (1) -->

<aside class="sidebar sidebar-main" role="complementary">

<?php
	do_action( 'before_sidebar' );
	dynamic_sidebar( 'sidebar-1' );
?>

</aside>

<?php
}