Ahh, okay. Thanks.
http://x5b.xanga.com/d4cf807009032274185349/w218593002.png
Edit: Fixed link. I just realized that I was linking to a jpg when I wanted to use a png.
Edit #2: Never mind! I decided to test out the link to the png and it worked. ^^ The signature settings page don’t list any file type restrictions, but maybe it was cuz it was a jpg?