click on "my profile" at the upper right. You may have to log-in so do so if needed. click on the "view/edit my profile". scroll down to the Avitar and click. Another window will prompt. There you can click on one of the avitars provided or choose your own by entering the url code of the image you'd like to use. Click the button to the right of the addy you entered, and it should view in the preview window. If it looks good, click accept and call it a day.
Hope I didn't forget anything.
Chris