Once you post ten times you can put in an avatar. And a signature. When you've posted ten times go to your user cp. Then on the left side of the screen there will be a couple boxes and one of them will have Edit signature and Edit avatar in it.
welcome to TDL ! Hope you have fun while you're here ; oh and for the avi posting thing, you have to have up to 10 posts in the forums; i know 'cause dayhawk68 told me that when i first got on ; she's very helpful