The Menu Editor displays the menu in a structured multi-level arrangement of entry items. This allows you to fold and unfold categories of links making your menu easier to manage.
Add a Menu Item
Click on the 'Edit this Menu' icon 
A new Menu will begin with one entry called Menu, as seen here.
Right click on Menu and you will see the standard options for Adding or Editing a menu. You can add new menu item above, below, or as submenu. Any of these selections will invoke the Add New Menu Item window. Complete the form selecting a link for that menu item and click 'Apply' to save.
Edit a Menu Item
Right click on item you would like to edit and select Edit Menu Item. Complete the Edit Menu Item form and click 'Apply' to save the menu item.
Delete Menu Item
Right click on item you would like to delete. Select Delete Menu Item and OK the delete confirmation.