Hey, Keynote! Beleive it or not, "Amazing Grace" was one of the first sax solos that I played in church too!

Broraj, I would suggest that your nephew play songs that are simple and catchy. Especially songs that are familiar to him. That way, it will be easier for him to learn. Tell your nephew to keep up the good work, and know that we are praying for him - that God will continue to use and anoint him to play for the glory of God!
Be Blessed!
Ladymusic88