The process behind wind energy is pretty simple. It starts, of course, with the wind, which is actually a form of solar energy. Wind is caused by the sun’s heating of the atmosphere, the irregularities of the earth's surface and its rotation.
The wind turbine captures that energy through propeller-like blades attached to a rotor, usually atop towers to access faster, less turbulent wind. Turbines can operate at variable or fixed speeds. Most new projects use variable speed as it more efficiently converts wind to electricity.
For more, see How Does Renewable Energy Get to My House or Business?