1. Go to your name at the top right of the main menu and click it. A dropdown menu will appear.
2. Hit User Control Panel then the "Profile tab" On the right you will see "Edit Avatar"
3.Click "Choose file" from your own computer and find an appropriate avatar. It must be at least 90 by 90 pixels or 600KiB.
4. When you have found the appropriate avatar, click submit. Must click submit after uploading the avatar or it won't work.
Hope this helps!
Shekinah