1) Go up about 3" on the blue bar, click "user cp" all the way on the left side
2) Scroll down to "edit avatar" in the left column, click that
3) Either load your custom avatar from the web(just insert link) or your PC (browse for your pic)
4) Scroll down to "save changes", click that
I think this will take care of you, if not just let us know and we can help more from there.