Editing Menus
Firstly, click on Appearance at the Dashboard menu and select Menus submenu.
At the Menus page, you will pick the menu that you want to edit and then put the select button.
After selecting the menu you want, you can add the existing page into your menu.
You can find your existing page by "View All" or you can Search.
After you click Add to Menu, the selecting page will appear at the bottom of Menu Structure on the right side.
How to create submenu?
How to create submenu?
When you want to create a submenu, you can move slightly the selecting menu to the right of the parent menu.