Where is the value to put referiant in the care? How do I do the input? on 1996 Chevrolet Lumina

My car needs feon and I know you can buy referiant over the counter.

Asked by for the 1996 Chevrolet Lumina
If you don't know where the valves are you shouldn't try to repair it yourself. A/C systems work at high pressures and it is possible to hurt yourself, not to mention bad for the environment if freon is released into the air. BTW im a MACS certified A/C tech.