I'm guessing you're wading?
If you wanted a float, or a guide.. a few shops are having winter time specials
The Gallatin.. goes from Bozeman to Big Sky, along the highway - easiest place to fish by far. Lower Madison, is a little further, maybe 20 minutes from Bozeman, can be waded, lots of people do, but a better float river
These 2 shops have the best online reports.
Fins & Feathers
(you have to drive past this place to gget to Big Sky from Bozeman)
This shop is in BigSky:
Gallatin River Guides
From BigSky - you might run into West Yellowstone and talk to these guys:
Blue Ribbon Flies
That should get you started