You mean the avatar? Like mine says "this is the best avatar ever"?
Go to the iPadforums website, tap on "user cp" at the top.
Scroll down and on the left you will see "edit avatar".
You can upload a picture, (requires a computer), or paste the link to a picture.
Remember: pictures have to be like 19kb. (which is VERY small)
And this has nothing to do with an iPad 2, so you could have posted in like "general discussions".
And also, remember to search! We already have a couple threads on avatar changing.