Go rent the movie. You won’t get the whole experience (which is to say, quite crazy – dressing up as transvestites, going to the theatre, singing along, being crazy, throwing toast, etc), but that’s fine, your first time is more than fine being the movie.
The movie itself is high quality, it’s not a cam or anything, it’s a full production in the same vein as Cats or Phantom of the Opera (in that it was/is on Broadway, but there is a film version available).
It is a completely unique piece of cult history, and while you won’t have the same experience that people had when it first came out, you’ll still have a great time. Watch it with as many friends as you can get :)