Editing Menu Structure
Use Add New Item, Remove Item, Move Item... buttons under the menu structure treeview to add new items, to remove items, and to arrange items into the menu hierarchy.
You can enter information for each individual item, such as text and link, as you populate the menu, or you can do this later.
Creating a submenu
To create a submenu click Add New Item and then move the new item to the right by clicking Move Item Right .