Airplanes fly because the design of the wings produces lift that counterbalances the weight of the aircraft. Air flows more rapidly over the top of the wing than underneath it, which reduces the air pressure above the surface. The higher pressure below, exerted over the surface of the wing, pushes the aircraft upwards. Achieving lift requires enough forward speed to keep the air moving fast enough to create this force.
The pilot uses three sets of control surfaces to direct the plane through the air. When each surface moves, it alters the airflow over that part of the plane and changes its direction. The rudder is attached to the vertical tail fin of the plane, and causes the plane to turn left or right horizontally. The elevators are attached to the horizontal part of the plane's tail, and push the nose of the plane up or down when moved. The ailerons are flaps at the rear of each wing, and when one is raised and the other lowered, they cause the plane to roll left or right. By manipulating each of these sets of control surfaces in concert, a pilot can cause his plane to execute many different types of maneuvers.