The term for the personal little pictures is an avatar. There are all kinds of instructions for doing things on the forum, including changing your avatar.
My avatar is a photo I took in my backyard pond. Brett's is a photo I took while we were stranded in Idaho.
The instructions can be found by clicking on the "forum" button at the top of the page. Then the fourth forum under "Airstream Community Forums" is "About these forums, How-To's & more..."
Here is a link
to that Forum
Look through there for all kinds of good information.