If you want "avatars" (those little pics in your profile area) then you need to be a BC4x4 supporter.
To display images in your message, you have two options:
1) Become a BC4x4 supporter and you can upload a pic to any message to post to the board.
2) Post your picture to some other website and link to it. Note, this does not work with some of the popular photo album sites.