Your avatar is the picture that shows up next to your posts. To upload you avatar, go to your "User CP" and click on "Edit Avatar" under "Settings & Options". The instructions are pretty clear from there on. =) Your avatar is different than your profile picture.
Okay. Are you talking about the "Horse Forum [photo] Contest"? If so, there is a button on the right side of the home page that you can click on to view and change your subscription. Voting doesn't start until 2 days from now (will you please vote for me? =P).
In order to ask a question, you must start a new thread. To do that, go to the home page and click on the sub-forum you want to put it in. Once there, there is a button (both at the top and bottom of the page) that says "newthread". Click that button and type away! Remember that once you post, you only have a short amount of time to go back and edit the post.
One other thing. When you reply to someone who wrote on your wall (like I did) you go to their wall to reply (click on my avatar to go to my wall). =)
I'd be glad to answer (to the best of my ability) any more of your questions!