manhex -

Welcome and greetings from SE Idaho.

If you like to read, I would suggest starting with "Reading The Water - A Fly Fisher's Handbook for Finding Trout in All Types of Water" by Dave Hughes. Next would be Dave Whitlock's "Guide to Aquatic Trout Foods - Second Edition."

As a practical matter, I think it is much easier to learn trout fishing on SMALL creeks and streams than on BIG rivers. Little fish in small creeks do all the things the big guys do, so when you figure out what they are up to, it is relatively easy to transfer that knowledge to big fish in big rivers. With the caveat that small stream fish are really aggressive and rarely selective, and big river fish can be pretty picky.

It's not clear if you were casting 40' - sounds like you were actually casting something less than that. If a novice is out there casting 40' in fast water .....

Also, there is a bunch of stuff on this website that will help you find more questions to ask. Fire away.

John