Register and call wdiget area in wordpress

Widget.php

 
<?php
/**
* Register Widget Area.
*
*/
function wpgyan_widgets_init() {
 
register_sidebar( array(
'name' => 'Header Sidebar',
'id' => 'header_sidebar',
'before_widget' => '<div>',
'after_widget' => '</div>',
'before_title' => '<h2 class="rounded">',
'after_title' => '</h2>',
) );
}
add_action( 'widgets_init', 'wpgyan_widgets_init' );
 
/**
* call Widget Area.
*
*/
if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('mailchimp_story_widget') ) :
endif; ?>