register sidebar wordpress

1/**
2 * Add a sidebar.
3 */
4function wpdocs_theme_slug_widgets_init() {
5    register_sidebar( array(
6        'name'          => __( 'Main Sidebar', 'textdomain' ),
7        'id'            => 'sidebar-1',
8        'description'   => __( 'Widgets in this area will be shown on all posts and pages.', 'textdomain' ),
9        'before_widget' => '<li id="%1$s" class="widget %2$s">',
10        'after_widget'  => '</li>',
11        'before_title'  => '<h2 class="widgettitle">',
12        'after_title'   => '</h2>',
13    ) );
14}

1<?php if ( is_active_sidebar( 'your-sidebar-slug' ) ) { ?>
2    <ul id="sidebar">
3        <?php dynamic_sidebar('your-sidebar-slug'); ?>
4    </ul>
5<?php } ?>