Once he realises he likes it I would get him a casting lesson to ensure he has no bad habits
I am sure once he he gets the hang of casting and hooks a fish or two he will be hooked for life
Fly fishing can become a big investment, Its all about what you want to fish for, small trout, Cutties, Pinks Salmon, Coho, Steelhead, Springs, Chum, etc
Then theres the different lines, floating, intermediate, sink tip, full sink (in many weights), all the different flies, wet, dry, nymph, streamer etc
and i won't mention the different rods and reels
but with a simple set up you can catch fish and have a lot of fun
Lake fishing is the best way to start, but like i mentioned not much shore access, I started this way but soon got frustrated with not be able to get to the fish due to the trees stopping my cast or that the fish were further out
So i invested in a basic float tube, and it opened up way more options and places to fish.
River fishing can be good but again the trees or brush can hider your cast, plus the flow of the water changes everything
I could help get him set up depending on what gear he has
I live in PoCo so I could meet you both at Lafarge sometime I could even bring my float tube so he could have a go around the lake with it