when u sign in, click on PROFILE, ull see it on the top right of ur screen. when in the profile menu scroll down to the AVATAR CONTROL PANEL. once there u can upload a picture from your computer (max 80x80 pixels, 15kb) i think..., then click submit once uve chosen the file. u can also upload the avatar from a website, and that option given as well.
hope that helps, im not very good at xplainin stuff :?