Each artist(s) will be there doing a set. They will play tracks of their own, and of other producers. There will be set times posted online and somewhere at the event. This is highly likely but sometimes it doesn't happen. Deal with it.
When everybody shouts and cheers, shout and cheer with them. The occasional classic will get dropped. Everyone will go mental. You won't know the classics but just follow what other people do. This includes not leaving enough room for your neighbour to nod their shoulders, buying knock off brown mandy from some young, way too happy twat in skinnies and a yellow bomber jacket, shouting the same request at the DJ for his entire set, and telling the MC when you see him outside "I don't normally like MCs...but". Be sure to visit the merch stand first thing and but a T-shirt to wear over your current T-shirt. Make sure your New Balance trainers are looking pristine.
Fuck it. I've kinda lost the tone I was going for here. Just go along, get fucked up (if that's your thing) and have a great time.