That is a scary venture you're attempting. Teaching someone who has never sung before is pretty tricky. You might want to see if there is anyone around (choir teacher, a church choir director, a voice student at a college, etc.) who has serious music and vocal knowledge who would be willing to work with this guy. I only say that because it is risky to teach someone "how to sing" when you aren't educated in that area. I've seen a number of people have to essentially have their voices "stripped down and re-built" when they finally get real singing lessons because of previous bad training. I'm sure you are a very talented singer and you may be great at teaching, but the things that you know about how to use your own voice may not be right for his voice. Does that make sense? So, look into finding someone who can safely teach him and best of luck! I hope he learns alot and becomes a fabulous singer so you can play Aida!