How to add a new sidebar for yours theme. WordPress

Post this code in your theme function.php

// Register Sidebar
add_action( 'widgets_init', 'mytheme_sidebar_init' );

function mytheme_sidebar_init() {
register_sidebar( array(
'name' => esc_html__( 'Main_sidebar', 'clean' ),
'id' => 'primary-widget-area',
'before_widget' => '<li id="%1$s" class="widget-container %2$s">',
'after_widget' => '</li>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>',
) );
}

Now you can output the sidebar to any file in your theme, such as single.php
To do this, use the code below.

In which it is necessary to transfer id to a sidebar which needs to be displayed

<?php
dynamic_sidebar('primary-widget-area');
?>

But if you need to change the wrapper of your sidebar, you need
change

<?php
dynamic_sidebar('primary-widget-area');
?>

on

<?php
get_sidebar('nameformysidebarfile');
?>

Then create in your theme directory file sidebar-nameformysidebarfile.php and in it already add

dynamic_sidebar('primary-widget-area');

For exemple

<aside id="sidebar" role="complementary">
<?php if ( is_active_sidebar( 'primary-widget-area' ) ) : ?>
<div id="primary" class="widget-area">
<ul class="xoxo">
<?php dynamic_sidebar( 'primary-widget-area' ); ?>
</ul>
</div>
<?php endif; ?>
</aside>