You go to a small dingy room with a desk and a computer.
You sit there, typing away at whatever it is you must type away at.
You do this for 8 hours a day, Mon-Fri.
After 21 days, usually at a stipulated date, an anonymous benefactor deposits a sum of money into your bank account.
Immediately thereafter, several anonymous extractors remove portions of the money.
Thereafter the earlier thereafter, you transfer what little remains into other anonymous collection agency bank accounts.
With what you have left over you can either a) buy Arx, or b) eat.
And that is how you earn Arx.