Start by checking the plane out carefully. Make sure glue joints are all goood, radio is mounted right and control rods are all solid. Once that is done, make sure the batteries are all charged right, and test fly it. teach him as you do things so he knows what you are doing. then put him on a buddy box up high and start slow with him, working on turns and holding alt. Then progress as you see fit. Don't go too fast and don't scare him.

Good luck. you will get a lot of satisfaction working with him, and may even make a good friend.