Well, on the main page of the forum, if you go down enough, you'll see a forum called clubs, right? if you go in there, go into the Sinnoh Club, and use the form I gave for signing up (in the original post), I'll add you as a member.
It's still pretty new, so if you'll sign up, you'll be the second member to join! The first three members get a free rank up by the way.
When you submit... Have fun!
Ok, well first of all, you make a first post with the Member List, ranks, rules, infractions, etc. You get it all.
After that, you post it in the forum Clubs, and it'll go to an Admin, that admin then decides if it's good or not, if it's good it gets accepted!
PS, would you join the Sinnoh Club? Just wondering, since it got accepted.