Pitch is the angle of the blades with respect to an imaginary flat disk cut up into blades.
In an efficient blade the pitch varies, being large near the hub, small at the tip. This is because the direction and speed of the wind as experienced by the blade is different at different radii. Like a sailboat, an airplane wing, or a propellor, the blades "sail in the apparent wind" - which is the combination (vector sum) of the actual wind with the wind from their own motion. Near the hub they experience mostly the real wind, running nearly parallel to the axis and moving rather slowly. Out near the tips they experience several times the windspeed from their motion as they do from the actual wind, with the combination much stronger and coming nearly from the side.
Because the wind is slower near the hub you need a wider blade there to be as efficient. (This also helps with blade strength - blades must be strong near the hub due to leverage.) But most of the power to be had is out near the tip, so designs often don't bother to taper as much as would be optimum, or quit fattening for the innermost part of the blade (where you'd be using an enormous amount of wood to collect a tiny bit of extra power).
Your plans will have the angles, shapes, and sizes.
The airfoil shape is partly to reduce drag but mainly to provide lift, just as with an airplane wing or propellor. In a turbine, the purpose of the lift is to pull the blade around while slowing the wind down. So the lift is angled to pull the blade both toward the downwind side and around the circle, while sucking the air behind the balde back in the upwind direction. If you don't use an airfoil shape your blade depends entirely on an "airscrew" effect (a "drag-type" turbine). Without the lift pulling the blades around you get much less torque and thus much less power.
A wind turbine may LOOK like a propellor. But if you look closely you'll see that the hump of the blades is on the back, rather than the front. This is because a propellor's job is to pull the air backward and the propellor forward, so the lift needs to be on the frontside, sucking the air to the rear and the blade forward. But a turbine's job is to spin itself by slowing the air, so the lift is on the back side, sucking the air back in the direction it came while pulling the blades both to the rear and around.
Does this help clear things up?
