93 GMC Sierra A/C compressor replace.

What is the procedure for replacing the a/c compressor? How do I add the oil and how much and what type. Thanks!

I recommend purchasing a service manual for your truck. I bought a Chilton manual for my 2000 Sierra at Pep Boys for about $20. It will give you step by step instructions for performing almost any kind of repair for your vehicle as well as specifications ( fluid types, quantites, etc. ).