The Wizard101 Message Boards now have a selection of avatars for you to choose from. To change your avatar, you must have made at least one post on the Message Boards. To the left of your post, below your name, you'll see the default avatar. Click on the avatar and a pop-up will allow you to choose a new avatar selection. You can change your avatar selection as often as you like.
We do not allow players to upload custom avatars and will not be adding that feature.