1: Once The Pantograph Extensions plugin is activated Mega Menu is available in your admin panel dashboard.
2: Enable Visual Composer for Mega Menu
a. Navigate to Visual Composer > Role Manager
b. In Post Types choose ‘Custom’ and then make sure mega_menu is checked.
3: Now add mega menu item in Main Menu from the Appearence>Menus and click on Screen Options to expand the options. And check the Mega Menu and CSS Classes item. And select Main Menu from Select a menu to edit: and press Select button.
4: Now you are able to see the Mega Menu in left side, And you can select this mega menu item and click on the Add to Menu button. At now you drag the mega menu item and make a child for a parent menu. In the parent menu need to expand and add css class ‘dropdown megamenu’
Finally, Save Menu from right side.