Rules-Economy:
If you are in debt, you will be charged 5%/week interest until you are back even. If you drop below -$500k, you must get out of debt within two weeks or you will be fired as general manager because the team goes bankrupt.
Improve your arena, fire/sell unwanted players, hire PR manager, play with ticket prizes, train players the right wa and most importantly win, win, win - profit comes with it.