As a newbie go very light.
Weights first then cardio.
Look up some basic beginner videos on YouTube to give you some ideas but most people do split days so you might split upper body / lower body into different days and then have one day where you do a full body day (but not as many concentrated on each area) .
Essentially you start as light as you need to, just because you can lift a weight doesn’t mean it is the right one. Ideally you’d be able to achieve about 12 reps but no more, if you can do 30 reps it’s too light, if you can’t manage 8 it’s too heavy.
There are methods to little and heavy or high reps light weights but I’d suggest for beginning to just start with weights that feel comfortable for 10-12 reps.
And you don’t need to do 100 different moves. Doing 6/8 different exercises for upper body with 3 sets of 10 reps would be totally sufficient. Then tag on some cardio if you like, I love will walking on the treadmill. Go at a decent speed - not a jog but a quick walk and whack up the incline.
I would really recommend youtube, check out basic gym for beginners. Find someone you like the look of and watch a few vids.
You will ache - that’s totally normal, it still hurts and aches even when you’re years into it. But it shouldn’t wipe you out to the point you can’t walk for a week after.
Most gyms will give you a free session to learn how to use the machines, it’s not a PT session but they’ll walk you round and show you what’s what.