Yep, it's called an avatar, common in most forums...hmm, there's a 90x90 pixel limit, I think that's it, so if the file is too large it won't work (Mine is like, 90x87 so that's a good idea the limit of how big the pic can be),
if it fits, then it should be able to work if you copy the url into the avatar section of your usercp...or just save it to your comp and browse for it (which might be easier to use if you can't isolate your picture on the website) I hope that makes a little sense.