I see how when I drag a menu bar on the canvas it creates a menu for the top level items in my site, but how do I create one for *all* the pages?
By default, the Menu Type option for menus is set to Top Level Pages. You can change this behavior by choosing Menu Type > All Pages from the menu options. The steps to do this are described in Adding a Horizontal Menu widget
North America
Europe, Middle East and Africa
Asia Pacific