There's more insight on my issue in this forum post from a short while ago.
When I drag things over to the white space in the upper right hand corner of the screen, the widgets don't stay.
I was told that I needed to select something from the widgets themselves first, but when I click on them, nothing happens.
I use Firefox most of the time, but this issue occurs even when I switch to other browsers.
So my questions are:
1. Do I need to be able to expand the menu widgets before I'm able to place select pages in the menu of the site?
2. What do I need to do to be able to build a custom menu?