Ok, so I figured out my problem. I didn’t pay enough attention to my styles. The sidebar was missing all of the height and width information! Rookie mistake.
Sorry, I did a poor job of explaining. There are three background files. One for the header, which is showing at the top. One for the content, which is showing on the left. And there is a third, which should be the sidebar. It SHOULD appear under the gray strip in the header and to the right of the content. It shows up under media in page info, but not on the page.
I discovered that the footer is actually working. I was coding much too late and didn’t realize it was blank!
