I JUST GOT MY FIRST JOB

Idk when I start cause it's a brand new store and they aren't 100% certain on the opening date due to Covid. It only $7.50 an hour and I'll probably only start off with 25 hours, if that, but I'm glad to finally have one after searching for a place that would hire me for about a year or so.

I'm sure they'll tell me all of this when I get the call for when work starts up, but do I go in the back door? Where would I sign in or whatever? Would there be a lunch area? Like I said this store is brand new so idk they lay over of anything over there. I live in a small town of probably 5,000 and I'm sure this Dollar General will be like all the others, but I'm just nervous. I'm terrified and yet so relieved to finally have one. I'll finally be able to stop relying on others and just be an adult for once.

Also how do jobs drug test? Is it a pee test? I don't do drugs, but I'd just feel weird peeing into a cup.