A few basics. A dry fly floats. A wet fly sinks. Most of the time, you fish one or the other. Sometimes you fish two flies at once. The second fly is called the "dropper". See the picture.
In this set-up, I was using a tan elk hair caddis dry fly as my strike indicator (think bobber) and a olive bead-headed hare's ear wet fly in the dropper position. The two flies where separated by about 15 inches of line. Fishing this set-up allows for two things. First, you figure out twice as fast what the fish are looking for. Second, the wet fly goes down to where the bigger fish are. Trout bigger then 10 inches are pretty wary.
This was my first time using a wet fly. I was happy with the results. I caught an 11 inch rainbow on the hare's ear.
I've got a lot to learn. Maybe I'll take up tying my own flies. That would be cool to catch a fish on a fly I tied myself.