You need to have sent at least 50 posts I think to get more priviledges. I think the best way to get your post numbers up, is to play the word association games, it takes a little bit of time but by playing the games you can build your posts up quite quickly.
Signature wise, you get more space the more posts you add. If you read the technical help section on the forum, it should hopefully tell you how to get sparkly bits and tickers for your signature.
Hope this helps xx