How do I create a submenu?

First you add a page to the sitebuilder in the 'normal' way, fill it with the information you want.

Save your edits and go back to the same page.

1. Now choose the tab: Other Settings

2. At Main page ==> subpage you choose the main page: So here it is: Possibilities

If you save this you will see that this page has become a subpage (menu).