Lots of people ask, only few get an answer.
Step one 
Make sure that you are connected to the site, and scroll to the top of the page. Click the "edit your profile" button near your username and control panel.
Step two
Find an image that you would like to use, and copy the url (right click, "copy"). Make sure that the image is jpg.
Step three
Scroll down until this box comes into view, and paste the url there. (right click, "paste")
Step four
Click "update". You're done!
* Note* - If your avatar doesn't show up, make absolutely sure that the image is in jpg format. If it isn't, save it to your computer, open it into an editing program, and resave it as a jpg.Hope this helped! Sorry for the sloppy handwriting, I'm left-handed.
