I went fly fishing with my father in law last year and got hooked. So when a friend offered me his never been used redington 8' 4 wt for 80 i snapped it up. But im at a loss. It came with one box of flys but they are for bc streams and im in central alberta. I want to order more flys from Icky Fly Works but im not sure what size i need and what would be the most effective in my local waters for what time of year. Learning bugs but havnt found a good reference guide yet. Thanks for any replys
Your 4wt should have no problem throwing the vast majority of those flies. Only when you start throwing large streamers will you encounter a problem.
The size is more to do with hook sizes used and the size of the fly. See Caddis on the Bow River for example. They range in size 10-18, one evening you might see tiny ones sized 18 then later in the season you may see huge ones in size 10. The various sizes help you match imitations with the natural fly. It's a good idea to carry the same fly in various sizes, trout can get really picky about sizes.
When i first started i just googled them. I don't recall where they came from but they are out there, i recall seeing charts for all the major river systems.