There are 3 menu locations in the theme:

• Primary Menu
• Footer Menu
• Logged In User Menu

In which, you can turn on Mega Menu feature for Primary Menu (beside the default multi-Level Dropdown Menus style) in Theme Options > Theme Layout > Enable MegaMenu. Mega Menu has 3 sub-level menu styles including List Style, Column Style and Preview Mode. Please check next sections to see how to configure the Mega Menu.
Logged In User Menu is the menu on top-right of the page and only appears when users logged in

If you have imported demo content, go to Existing Menu or else go to Creating a New Menu to create a new menu.