How do I get me Ac working ?

A cheap way is to buy a refrigerant for the car, like A/c pro or something

The refrigerant will only help if the system has a low charge. Go this route if you are confident you will not over charge it and are comfortable doing the work yourself. Otherwise let a trustworthy shop do the diagnosis and repair.

I agree with Taver. If the system needs refrigerant that means the original refrigerant has leaked out somewhere. Refilling the system rarely works. Spend that money on a proper diagnosis. And brace yourself. Air conditioner repairs are rarely cheap.