Forums → Support Forum → Rank

By gaining AP Points.

Ways to gain AP Points:
1.Rank a Game-2 Points
2.Comment on a game/profile-2 points.
3.Make a forum post-1 point.
4.Make a game-20 points (?).
5.Get a merit-25 points.

Spamming is looked down upon though.

Also, for more questions you should take a good look in the Newcomer's section, especially at the stickies, as these are there to answer questions like this.

Is there a breakdown of point rankings? How many points for each rank?

You will find out when you acheive that amount of points.

I dunno, I usually look at GMSaitanGm's Profile