Okay, so here's the basics: WHAT IS DRAG: Drag is basically all about messing with gender roles, and it's huge in queer culture. People dress up as a gender they are not, with really exaggerated makeup and clothes, and they perform for an audience. Most often you'll see what we call drag queens (men who perform as a female identity), like Countess Chocula (you remember her from speed dating, right?), but there are also drag kings (women who make themselves a male character to perform as) and sometimes you'll have someone who performs as a nonbinary identity, which there's not really a consistent term for.
WHAT IS DRAG PERFORMANCE: Sometimes it's just a pageant, which is like a competition for who's the prettiest. They have those at Spectrum every few months or so if you ever want to go to that. Lip-synch performances are also really common (where the queen or king pretends to be singing a song that's playing through the speakers and dances along with it). And you also have what they call "comedy queens" (or kings) where they basically do stand-up comedy in their drag persona and work the crowd. That's like...club drag, though. Sometimes you'll have something like Drag Story Hour, where a drag queen reads stories to kids at the library, and that's drag performance too, but it's not the kind of thing you'll see at the club. Drag performance can really be anything anybody decides to do in drag for an audience.
WHAT TO DO AT A DRAG PERFORMANCE: Cheering is expected, and you'll pick up really fast what kinds of things people say to be encouraging. You're also expected to tip, kind of like at a strip club? That's how the queens usually make most of their money from a performance. They'll come through the crowd at different parts of their performance, and when they do, just pass the queen a small bill or two, either by handing it to her or tucking it in some part of her costume (cleavage is popular). Obviously don't get too touchy, and you'll want to be efficient about it. (I usually just hand them a few dollars and say "you're so beautiful" or "your act is great!" or something like that, because I'm scared I'll screw up if I go straight for putting money in their cleavage.)