I know this because I recently dealt with this myself.

Go to your website then click Customize. Go to Menus. You should have a menu labeled “Header” in there already, but if not, then Create New Menu and set that menu to Top Menu. After this, you’ll be able to Add items, or the pages you want to add.

The banner setup will be in [box] Banner image. One step that might not have been setup is in Customize > Homepage Settings; in this section, go to Homepage and set that to your page that is setup with the Front page template.

I asked Box for help and they setup the page for me. I might suggest doing the same thing if these steps don’t work.