There seem to be a little flaw in the picturecode. And the rank is not something for you to pick. The rank will increase with the number of Armor points. Some have the list of AP vs rank list on their profile.
You can't see your rank until you have a certain amount of AP, which is gotten by posting, commenting, rating games,etc. The fact that your rank showed up simply means you've got enough AP to become a wood serf.