You can't edit the wiki until you're at least a "Lance Corporal", which is at least 20 posts. It's an anti-spam thing (you'd be surprised how much spam we got on the previous wiki).
At this point, however, we haven't really had enough issues with forum spammers to require that high of a post count. Maybe when Kornel gets back to create the AliensRL Wiki, he can relax the edit requirement to something like "Private FC" (5 posts).