Agree with Fox in terms of basic mechanics. They just plain catch fish though. I've caught fish in every conceivable fashion with them...drifting, swinging, stripping, upstream, downstream, 90 deg...just having the fly dangling in the water while I was doing something else.
The standard technique with them is to cast them across the stream from you, let them drift downstream and allow the line to tighten as this happens. Once it does the fly will "swing" across the current and end up nearly directly downstream of you. Once it does, strip it back towards you, with pauses in between the strips. Strikes can happen at any point in this process, but most often on the beginning of the swing IMO. WB's make a good beginner fly because you get to practice 3 different techniques all in one cast (drift/swing/strip), and again, they're just plain catch fish.
For Trout, in clearer water I like olive, in stained water black. For Bass, white and chartruse. I like mine with a beadhead or some lead wraps, or both...you usually want to get them down a bit. The swing and strip will cause the fly to rise in the water column, which sometimes triggers strikes I think.