Vigor A/c Question?

Hello, I have a '92 Vigor and recently busted a pin sized hole in my a/c condenser and all the freon got released. Well I was able to patch the hole w/ some jb weld and am possibly able to get ahold of some r-12 freon that i am sure what my car uses. Well my question is , is where to install it (where to hook the hose to), and how to use the guage thing. i believe all you need to have is the gauges(w/ hoses) the can tap thing and the freon. i might be wrong. i know this job has to be done by a certified machanic, but it can't be that hard to do yourself.

oh yeah , i called autozone and they said my car holds 3 oz. of freon, does that sound right? seem to little to me.