Your rank is based on the number of posts you make.
New Member: 0-49 posts
Junior Member: 50-99 posts
Full Member: 100-249 posts
Senior Member: 250-499 posts
Hero Member: 500+ posts
There are two exceptions to this. First is the rank of administrator, which only belongs to Nils, the person who runs Deckstats. Second is moderator, which can only be given to you by Nils. We currently have three moderators (AeroSigma, G. Moto, and Mnemosyne), but each of them has been inactive for some time now.