<?php wp_nav_menu( array( 'theme_location' => 'secondary' ) ); ?>
<?php echo SHOPME_HELPER::main_navigation('', 'secondary'); ?>
<?php echo SHOPME_HELPER::main_navigation(); ?>

https://www.thewordcracker.com/intermediate/how-to-add-a-new-cumtom-header-menu-in-wordpress/

https://developer.wordpress.org/reference/functions/wp_nav_menu/