Add back Spacious slideout menu

First time using GeneratePress, with Spacious.

I mistakenly deleted the Spacious sidebar/slideout menu when initially poking around. I know, oops.

How do I add it back?
Or, can I recreate the same thing using the Menu Plus module?

The site should only have one visible page right now, but the other pages are showing in the top menu.

Please point me toward the correct documentation.
Many thanks!

Marsha

The page I need help with: [log in to see the link]