After creating your menu, you need to assign it to a menu module published in the menu module position. To do so, just go to Extensions > Module Manager, create a new Menu module and publish it in the menu position of the template.
Module in Menu Position
You can also publish any module in the menu position. The module name is used as menu item and the module content appears in the dropdown.
Menu Styles
There are three different menu styles, the Navbar and its mega dropdown as a main menu, the Navs with the accordion effect in sidebars and the Subnavs in the toolbar or footer. Warp automatically styles the menu according to its module position.