I wouldn't recommend a/c system as the place to start gaining DIY experience, take it to a pro.

FYI: Various valves for a/c are visible on a/c hoses around rad. covered with caps. The valves themselves are kinda like tire air valves, I think the proper name is Schroeder valves.

98 Mystique LS v6 atx 110,000km
97 Contour LX v6 atx 125,000km
stock CD on LS, cass on LX
spoiler, tinted windows on LS only
4 wheel discs on LX only
All other available options on both