Ok I have no idea where they are specifically on your vehicle, but they usually have color coded caps and are red for the high side and blue for the low side. Lowside is usualy on the side with the airbox and High on the side oppsite that...
Since it dosen't seem that you have much knowledge about A/C, a few tips and safety things...
First off, usually if the system needs charging, then there is a leak somewhere. You might be able to get away with a simple recharge, but usually there is a problem somewhere, that needs to be fixed sooner or later.
Seccond, NEVER EVER use those "leak stop / sealer / A/C Fix in a Can" things. The sealer plugs up the system and makes it a $#@$@*&#$@*$ to fix later.
For charging, there is the standard manifold gague setup or a number of cheaper options. I would guess you are gonna go with the cheaper options.
The best of the cheap ones looks like a handle with a place for a R-134A can on the bottom, a trigger and a gauge, with a hose to stick on the LOW side port. The gauge will probably have some color-coded zones on it, but dont use them. Get a Haynes A/C book or similar and look up the specified pressures for your system.
The best time to work on A/C is a warm, but not too hot day like 60-70 degrees. Now that you have your charging thing with a can of R-134A on it, attach it to the lowside port, and start the engine and turn the A/C on. Let it run for a few min, and look at the pressure shown on the gauge. If it is low, add by pulling the trigger and filling to about midway of the spec's. It's probably better to do it in small bursts, and let the pressure stabilize. You don't want to overcharge it.
If you use a full manifold gauge setup, then remember to NEVER open the high side valve with the system running. This will case backflow into the can and blow it up, and you really dont want that to happen.
As usual, you're working with a running engine, so watch the belt & fan, dont wear a tie, etc
Hope this helps
