You go on to imageshack, log in or sign up, open a paint file or whatever your drawing program is, make it smaller, save it, go back to imageshack and it should be on Media Upload. Select the file you want to upload, change the size to avatar, and upload. If your logged in it should have a button that says "full size". Press it. Copy the url on the search bar, and paste it on the avatar change area where it says custom avatar in the url section. Press save changes and presto! You have a new custom avatar! Hope I helped! (And spelled everything right