In order to keep this site of a certain high quality caliber, access to editing the site is restricted. Access is granted primarily on an invite-only basis. Asking to be invited is almost certainly the best way to not be invited.
Actually, there is one way to get invited – write something awesome. Put it on the forums. People here will notice. Maps guides, vehicle guides, weapon guides, etc. A high percentage of the content on this wiki is based on forum posts in aggregate, or singularily.
If you want to know who's got what it takes, click here to find out.