The Advocator theme supports two header menu called “Header Top” and “Header Bottom”.
You can create and manage these menus by navigating to Appearance > Menus.
The steps to create a menu for your site are the same as you would any WordPress menu. The WordPress Menu User Guide will describe how to create a menu, add menu items, create multi-level menu items, and more. Simply add menu items from the Pages on the left column and drag/drop them into the order you want them to be in.
Once your menu is created, assign it to the menu location you’d like it to be displayed from within the “Manage Locations” tab: