The pitch angle is changed by the cyclic and collective as already mentioned. In forward flight the pitch angle is different (more) on the retreating side and less on the advancing side, this is called cyclic feathering. The angle of attack changes through flapping as well. Flapping alone wouldn't be enough to solve dissymetry of lift.
But take a look at the swashplate and blade angles if you move the cyclic forward. (on the ground obviously, engine off)