I was just given some St. Croix 5/6 weight fly rods. I live in the Bristol Bay area of Alaska. What can a 5/6 weight rod be used to catch?

I'm also looking for an inexpensive reel and proper line(as a beginner).

A few good places to shop would also be helpful.

I'm used to fishing with bait-casters and spinning rod/reel setups.

Any help is appreciated.