Adds multiple sidebars to any theme for WordPress

functions.php

<?php

// Adds Widget Area
// Register Widgets
function custom_sidebar() { 
	  
	register_sidebar(array(
		'id'            => 'my-new-widget',
		'name'          => __( 'My New Widget', 'text_domain' ),
		'description'   => __( 'This is my widget description.', 'text_domain' ),
		'before_title'  => '<h3 class="widget-title">',
		'after_title'   => '</h3>',
		'before_widget' => '<section id="%1$s" class="widget %2$s">',
		'after_widget'  => '</section>',
  ));

  register_sidebar(array(
		'id'            => 'my-new-widget-2',
		'name'          => __( 'My New Widget 2', 'text_domain' ),
		'description'   => __( 'This is my widget description.', 'text_domain' ),
		'before_title'  => '<h3 class="widget-title">',
		'after_title'   => '</h3>',
		'before_widget' => '<section id="%1$s" class="widget %2$s">',
		'after_widget'  => '</section>',
  ));
 
}
add_action( 'widgets_init', 'custom_sidebar' );