How do helicopters fly

Their rotors spin, generating lift. The tail rotor keeps them from spinning around. I dont wanna repeat what the others say.

A helicopter’s rotor blades r also shaped like airfoils & they work pretty much the same way as an airplane’s wings. But instead of speeding forward to increase relative wind, the helicopter rotates the blades while parked. The faster the blades spin, the higher the relative wind. Once the blades r spinning at 100% RPM, the pilot lifts the collective, which changes the pitch or angle of attack on all of the main rotor blades. The result: the helicopter lifts off the ground.

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its a complicated process, i used to work on them in the military..check out this site..

http://travel.howstuffworks.com/helicopter.htm