Did you read the FAQ? It says there that you need at least 500 posts to get your own avatar. At that point, you will become a "macrumors 6502". Higher post counts get you different titles (unless you decide to become a contributor, in which case you'll always be known as "macrumors demi-god" and can have an avatar regardless of post count).
Good call on setting that FAQ up - how many times has that come in handy already for ya?
And Solafaa, there is a myriad of information contained in the MR FAQs, I'd recommend reading through them before posting any further questions like this.