What do I do after getting accepted

My plan right now is to just apply everywhere I can and see which ones I can get into and I can just pick which one I can go to. But like when a college offers you a place at their school I dunno what to do next, like what do you say to them. Do you tell them your plan, do you accept every single place and then pick after GCSE Results, do you wait until all of them have replied and GCSE Results day until you finally accept one of them. Cuz I've just got accepted into a college and even tho I'm happy, I'm not sure if I wanna go to it and I wanna wait until all of the other colleges reply. So then what do I do, do I accept the offer or not. Just what do I say or do and whatnot

Edit: I'm talking about UK Colleges