Tough part about fly fishing in North Georgia is that a lot of places that would be great for it have close vegetation- making it hard for a novice. But there are some great spots
Cartecay River outside Ellijay; the Chattahoochee near Helen; the Chattooga on the SC border.

I’m partial to Rock Creek and Coopers Creek. Grew up bait fishing for trout on those creeks but I know plenty of people fly fish there.

Good article here http://https://www.gon.com/fishing/guide-to-states-top-trout-streams

Be sure to read up on GA fishing regs and be sure to get a license with a trout stamp. DNR will pop you for not having one.
https://georgiawildlife.com/Fishing/Trout