To create dropdown Submenus + Headings:

1. Access your Reverb Sites Dashboard
2. Click on the "Navigation" Tab
3. Click and drag a navigation link that you want to be a submenu under the top level menu.
4. Drag it to the right. (It should pop into place.)

You can create a third layer navigation by dragging another link under the second level navigation and additionally dragging it to the right.