If you get a recharge kit, I assume it is R134A all the refrigerant that is presently used, not R22. It's not hard to do (but of course should be done professionally with gauges by a tech who knows what it's supposed to read), anyway I disavow anything that I might tell you here, that may cause you to get hurt or worse,,,lol.
Once you find the right size connector in the engine compartment, that matches your kit, & bottle, I believe it goes on the larger gas line (low pressure), not the smaller liquid line (high pressure), start the car, & put the A/C on full then connect the lines, (hold the can upright so gas comes out, not liquid, this is important), then pierce the can, & open the valve the can will frost up while filling, be prepared. Continue to fill till the A/C gets cold inside, and, or, it stops taking the fill, then close the valve on the can, & undo the hose connection, if you need more then one can, repeat the procedure, until satisfied.
If anyone here that's more qualified would like to add anything, or correct me, please do, as I don't do this on a regular basis, although I think it's right.
I wouldn't recommend that you recharge your A/C by your self if you have never done it before. It is very easy to create more damage if you over charge the system. I would recommend you bring your cans of freon to a professional and pay to have them check it out. Putting too much freon into a system can cause damage and can wind up costing your more for the repair. Think of a car like the refrigerator in your house. You should not need to add freon unless there is a problem. "IF" you need freon then there is a leak in the system, it can be a very slight leak which can take months to leak out but a there is a leak. Having just 3 to 5 oz's low on freon can make the difference between cool air and cold air. A freon can is about 10oz. If you put the whole can in when you only need 3oz you can cause more damage to your system and can cost hundreds of dollars, like damaging the compressor. When all you needed was a simple O ring replacement to repair a leak. There is an old saying "penny wise a pound foolish". I don't think it is worth the risk. But that is just my .02
I agree with skipping the DIY...
find a good Indie shop that specializes in A/C work; every town has one.
They do it for a living and can run some quick tests to pinpoint the problem
and, do the proper repair, imo.
I've recharged a few cars already, it was fairly simple, no big deal, and usually doesn't require much Freon to get a good result, but if you have a leak it may not work. Basically if your compressor still comes on when you turn on the A/C you can usually refill with no problems, if it doesn't then you've lost too much Freon, and this may not work. My son is an HVAC tech with Sears home service, and we've done it together a couple times, plus I've also done it by myself.
I've recharged my 88' Monte Carlo SS, my 98' Dodge Neon, & my 96' Chevy S-10 pickup, myself, and a few more vehicles over the yrs that I've probably forgot about.