Night club photos- coving a shift with no experience

I've just been asked to cover comes work in a bar/nightclub taking photos. I do take photos, but just in general, but thats why i was asked as i know my friend who's shift i'm covering. Only thing is, i have no idea how to take photos in a nightclub/bar?! Do i just put the flash on! I have a Nikon D5100, nothing fancy, but someone please help!

Why don't you ask this person. Regarding exposure, and composition of photo's. I imagine that standing at a regular distance from subjects and including just head and shoulders would be best. But I have no idea what the "nightclub" wants.