Hey Mthunderwolf welcome to the board, and welcome back to fly fishing.
You live in a great area to be taking up fly fishing, so you should have a blast.
Ask 10 folks that fly fish about gear recommendations and you'll get a zillion different answers, but I'll give you my 2 cents with some specific stuff to look at and at least consider. I’d match up your rod with an inexpensive but decent reel and a “weight forward” (which refers to the taper) floating “5 weight” fly line to match up with your rod. The line will be designated something like "5wt WF-F" on the package. You’ll also need about 100 yards of 20 lb backing to go between the fly line and the reel.
You have a ton of choices at many different price points. If you buy them separately, an inexpensive fly reel will run somewhere between 30-50 bucks, a decent but inexpensive fly line about 25- 45 bucks and 100yds 20lb backing around 10 bucks, but you can often get a break on the price if you buy a reel fly line and backing together- typically the backing will be free and you get a bit of a break on the total cost of fly reel and line. And if you buy them together they can rig it all up for you.
There are a couple ways to go. For about 60 bucks all in for fly reel, fly line and backing:
LL Bean Quest II LA size 2 fly reel for 35 bucks. It’s a composite graphite resin reel that has gotten good reviews, and it will hold your fly line plus 100 yards of 20lb Dacron backing Quest II LA Fly Reel: L.L. Bean Reels at L.L.Bean
And you can also buy the reel pre loaded with LL Bean fly line, backing and leader for 59 bucks Preloaded Quest II #2 Fly Reel with 5 Wt. Line: L.L. Bean Reels at L.L.Bean
Another set up in this price range would be an Okuma Sierra S4-5 fly reel for 35 bucks (die cast aluminum reel) Sierra Fly Reels-Hook and Hackle
matched up with their "house" fly line (some forum members have been very pleased with these lines) for 25 bucks H&H WF-5-F Hi Floater Line-Hook and Hackle
Add some of their backing for another 6 bucks: H&H Backing - white - 20 lb.-Hook and Hackle
and the total for reel, fly line and backing comes in around 66 bucks or so total.
For a bit more at around 100 bucks the sponsor of this forum has a couple of reel, fly line and backing combinations that are a notch or two above these less expensive combinations.
Ross Fly Start 2 reel 55 bucks, plus Rio Mainstream fly line (45 bucks) plus backing (10 bucks) for 99.90 may be a bit better. The reel is made out of cast aluminum rather than composite resin, and the fly line is a bit heavier than standard (designed to help beginners cast easier)
ROSS REELS FLYSTART 2 FLY REEL (4-6WT)
or a Redington Red.Fly 2 reel 59 bucks plus Rio Mainstream fly line (REDINGTON RED.FLY 2 4/5/6 FLY REEL
5 bucks) plus backing (10 bucks) for 103.90 REDINGTON RED.FLY 2 4/5/6 FLY REEL
As far as a leader, I would get a 9 foot 4X tapered knotless monofilament leader and a couple spools of tippet 4X, 5X and 6X. The tippet is untapered mono, and you’d add about 2 feet to the end of your leader. (There’s a post in the FAQ section explaining the ins and outs of tippets). I would try to match up the brand of leader and tippet spools if you can. Look for names like Rio, Scientific Anglers, Climax or Umpqua.
For flies, your best bet is a local fly shop for specific recommendations, but for Montana you couldn’t go wrong with some tan Elk Hair Caddis in size 14, some grasshopper patterns in size 10, and a few black woolly buggers in size 8. There are a bazillion other patterns you could add, but those should be in your box for sure. I'm sure some of our Montana folks could weigh in on must have fly patterns out there but you could do a lot of damage with those 3 i bet. (Add some paste type dry fly floatant like DAB for about 3 bucks.)
Good luck. Keep asking questions, there's a lot of helpful folks here and many of them fish out your way. Good to have you on the forum.