no problem. all you do is find a picture you want to use, then cut it down to a 64x64 (max, it can be smaller) pic. then go to your "user cp" and select "edit options" and hit the "change avatar" button. it'll then give you a choice of loading from your comp or from a website.
i don't have the advanced graphics capabilities of some of the others, so i just find a groovy pic, and then use the microsoft photo editor to resize, and then crop out the pic i want.
hope that helps