"If someone could help me out that would be greatly appreciated!"
Face to face or over the phone can be far superior to forum text. At no point did I plug our products. In any case, I apologize to everyone for "just spamming"...
Joe, sorry for that, let me add some helpful information.
How were you fishing the Niagara in the past? What is your current/past set up? (spoons and cast and retrieve on the spin, floating on the spin, bottom bouncing on the spin reel, etc.) What lines are you currently running? Braid? Mono?
There are a variety of options, as everyone runs their own unique set up. Niagara gives you more room to play with varieties than smaller rivers.
For both scenarios, small and big water, you will want to start your pin with fly line backing. This is a light weight alternative to filling ~half your spool with main line which is heavier and would cost more. Fly line backing does not need to be replaced each time you respool your main line. Choose a colour you like. Backing strength doesn't play much of a factor, as you should never really end up into it when your fighting a fish on your centerpin. 20-30lb strength is average. Attach your backing to your reel using an arbour knot. 100yrds should do the trick.
Now it is time to start getting a bit more specific. Assuming you are fishing the Niagara for Steelhead on the float, I would suggest a 10-12 lb mono main line. You can attach this to your backing line using an albright knot. If you were running just Niagara, I would suggest 12+. Since you will be playing in some smaller water, 10 would be a more versatile line, but you are giving up some strength in that Niagara water. I have fished the Niagara for a few years now, and if those fish get out into some real current, a 10lb line can break you off as quick as those fish run out there(given you will be forced to run a smaller leader on 10lb main line than a 12+). General rule of thumb is to leave as much space on your spool as there is between the spool edge and backing. Most reels its about ~3mm from the outer edge of your backplate to where your spool attaches. Keep your line this far back a gain from the edge of your spool. (In total you are looking for about ~5-6 mm space left on your spool to the outside of your reel. There are plenty of mainline companies out there, take your pick. Tournament lines are stronger for the diameter of the line, but cost more. Usually about 250 yrds or so.
On your main line you will want to attach your float. Most guys run slip floats about 15grams. Lots of room to play with size to find a float that supports your shot and presentation that works for you.
Next you will want to run a XS barrel swivel. Attach this with an improved clinch knot to your main line. now on the other side of your swivel attach your leader line with another improved clinch knot. You always want your fluorocarbon leader line to be at minimum 2lbs test shy of your main line. In the event you get snagged up or your under enough pressure of a fish in fast water, your leader line will be what breaks and you will still have your float, and shot that is attached to your main line. Note that Drennan lines run stronger than they market. I wouldn't have a smaller gap than a 12lb mainline with a 8LB Drennan (as it runs closer to a true 10lb line). a 4lb gap is always a safer gap than a 2lb gap.
You can use as long as a leader as you want. In small water outside the Niagara you would probably want to run approximately a 3-4 ft leader. In the Niagara you can go up to 6-8 feet if the water is really clear (like it gets some days). The shorter the leader the cheaper it is, essentially. The less you will lose on a break off. The shorter is is, the spookier the fish will get. It is a trade off.
Everyone runs different presentations in the Niagara. Roe sacs, skien, beads, minnows, etc etc etc. Options and choices are yours.
Shot patterns vary in Niagara as well. A lot of guys are scared of attaching shot to leader lines. If you are using a weighted presentation (jig head etc.) You wouldn't have a need to attach shot to your leader. Most guys will bulk shot just above their swivel (on the main line) to get their presentation deep as quick as possible. Some will add smaller shot on the leader when drifting presentations with little to no weight like worms, plastics, and roe sacs.
I could go on and on but without hearing some answers for you it is hard to dial in and help you specifically. I hope some of this helps and you're gunna love hooking up to your FIRST FISH ON THE PIN !!!!!!!!! Fish on!