how make custom menu in wordpress

1function wpb_custom_new_menu() {
2  register_nav_menus(
3    array(
4      'my-custom-menu' => __( 'My Custom Menu' ),
5      'extra-menu' => __( 'Extra Menu' )
6    )
7  );
8}
9add_action( 'init', 'wpb_custom_new_menu' );
10

1<?php
2wp_nav_menu( array( 
3    'theme_location' => 'my-custom-menu', 
4    'container_class' => 'custom-menu-class' ) ); 
5?>
6