The credits are a little messed up at the moment, but normally you get money by posting (you get a little bit per word) or by performing a job (like recruiter, army member, Speaker of the Senate, etc.). The stars are also a reflection of your activity on the board, so if you keep on posting you'll get more of them, to a point.
To become a Citizen, apply
here by taking the oath provided and giving the name of your Taijitu nation (and your UN, if they are different).
To become a Senator you must have been a Citizen for 15 days, possess a UN nation, and have 25 forum posts, at which time you may apply
here.
Justices are appointed, as are Ministers, so our Delegate must choose you personally for such a position.
Here is a link to the Guide to Taijitu, which explains where you can go for different things on the forum:
Huzzah!
