How can I make Multiple Level Navigation Menus

Try

<?php wp_nav_menu(
   array(
	'menu' => 'Primary Navigation',
        'depth' => '2',
	'container' => 'div',
	'container_class' => 'sixteen columns'
	));
?>

Actually I followed this tutorial -> https://webdesign.tutsplus.com/series/building-a-responsive-layout-with-skeleton/

I completed it and was managed to make the complete template. But the problem is it only was the ability to display level-1 sub-menus. I’m guessing i have to change my code and styles a bit to add the multiple layered menus.

Can someone help me out?