Since Freon is a regulated material, you will need a license to purchase it from a store.
If you have it already, it is fairly easy to add. Just locate the schrader valve on the suction side of the compressor. This is the larger of the two lines (discharge is always smaller). Hook-up your hose/can and your off!
This is an over-simplified version, so you may want to consult a manual first.
