To understand how the Osprey flies, the basic thing to understand is that airplane wings create lift by deflecting air downward, benefiting from the equal and opposite reaction that results. Helicopters do the same thing with blades, which are rotating wing shapes like the airfoils of an airplane wing. Helicopter blades are thinner and narrower than airplane wings because they have to rotate so fast. These rotating wings are mounted on a central shaft. When the shaft is spun, lift is created.
When the Osprey is ready to take off, its rotors are in a vertical position. With the rotors mounted on the wings, it looks like a two-bladed helicopter. When the Osprey is in helicopter mode (on takeoff, landing and when hovering), the rotors generate lift. While in flight, the Osprey's rotors move down to a horizontal position. In this position, it is the wings that generate lift, like on a traditional airplane, and the rotors function as they do in a propeller aircraft. The Osprey lands like a helicopter by reversing the process, raising the rotors from a horizontal to a vertical position.
For more information on the Osprey and other military vehicles, check out the links below.