This is one I usually post for people to get started, so it should work for you as well. It's the kind of thing you might get in a gym of an instructor
Basic total body stuff 3 times a week.
Squats, 2 sets 10 reps.
Lunges, 2 sets 10 reps.
Deadlifts, 2 sets 10 reps.
Dumbell Bench Press, 2 sets 10 reps.
Bent over Dumbell Rows, 2 sets 10 reps.
Dumbell Shrugs, 2 sets 10 reps.
Planks 30 seconds.
You would do this every other day, 3 times a week for around 4-6 weeks, to adjust to the biomechanics of weightlifting.
For you, go for the lightest dumbeels possibles on small muscles, like say the little pinkies or as low as you can go and the next ones up for bigger muscles.
In his case, the ones you'd use for big muscles, he'd use for small ones, and then the next up for big ones.
I.E. you use a 1kg and a 1.5kg, he uses a 1.5kg and a 2kg, but what was use would depend on what was available. If you're not sure 1kg =2.2lbs.
Wih Barbells, for you, you'd use as small as possible, he'd go the next up. If the next one up was too big a jump in weight for him, I.E. 5kg, versus 2.5kg, he could get a couple of very small weight discs and attach them with clips or collars.
This system allows him to start with a little more than you, as he should be more muscular than you, because of natural adolescent development and more ability to produce Testosterone and growth Hormone, but the system will work for both, because none of the exercises would be things that are gender specific, or he might just cope with, but you wouldn't, unless that is you or he had initial issues with a recovering or old injury, or some kind of abnormality in musculoskeletal structures, I.E. he had a slight bit if Kyphosis of the upper spine, or you had a slight cartilage issue as examples, in which cases adaptations could be made to accommodate the problem(s) and find one or more workarounds.
A Gym instructor could advise further on an appropriate beginners methodology once the kind of physiological assessment I can't make, had been completed.