Help me - questions on circuit weight training

I'm going to my first night at Anytime Fitness, I have a four week pass and I think they were cutting me short yesterday when I signed up cuz it's not a full memembership. She didn't show me how to use any of the circuit machines & the location I signed up at is now closed for the week but thankfully I"m able to use it at the other location in town.

Anyway I want to do the circuit weights but have no idea what to use for an ideal weight, do I see how heavy I can do and lift a percentage lighter than that, do I just start light, what do you suggest for number of reps do I do 2 sets or 3 sets. I'm clueless & nervous because I don't want to hurt myself but don't want to baby myself either. I'm hoping the person at the other location in town is a bit more helpful & may even show me the ropes but incase they don't I want to be prepared.

Thanks fellow fitness peeps!