This is a much better plan for your nephew. Lisa posted it to Ms.T. I will just leave it un-quoted so it's easier to read.

Orginally posted by Dane/Lisa:
Here's the program I put my DH on--he is also a newbie. We started him on just 2 days a week. Maybe you might like to try it? After 2 weeks it could be modified to 3 times a week.

5' warmup on the stationary bike, just enough to get the blood flowing.

5' dynamic stretching warmup...I'll get you some links for that.

Then
Squats, 3 sets of 5-8 reps, using just enough weight that you could ave done another, but not.
Rest 1 minute between sets.
Romanian Deadlifts, 3 sets of 5-8 reps, 1 minute rest
Bench Press, 3 sets of 5-8, 1 minute rest
Bent Over (Barbell) Row, 3 sets of 5-8, 1 minute rest

These exercises can be done with the barbell or dumbbells.
That's it!

Then a few days later, Workout #2:
5' on the bike, 5' dynamic stretching
Front Squats, 3 sets of 5-8/1' rest
Deadlift, 3 sets of 5-8/1' rest
Overhead Press, 3 sets of 5-8/1' rest
Chinups (assisted if needed), 3 sets of 5-8/1' rest
(Again, you can use dumbbells for these if you want)
Can follow the workout with 15 minutes of cardio if desired.

Don't be intimidated by the exercises---look them up on exrx.net, and try to focus on form, rather than on the amount of weight you use. Expect to use light weights with these, but try to challenge yourself. After you get comfortable with the exercises, and can complete 8 reps with ease, it's time to move up the weight.

I should add that your diet is 80% key for success, so be sure you got that straight,