What is the procedure to turn an airplane when it flying?
Ailerons are but one type of primary flight control surface, which are used to roll the airplane about the longitudinal axis, thereby directing the lift vector generated by the wings from the vertical to the direction of a desired turn, thereby providing the required force to cause the airplane to change direction.  Ailerons aren’t the only primary flight control surfaces which can do this; other types can include flaperons, differential elevator inputs and differential spoilers.

Rudders are used to counter adverse yaw caused by the difference in induced drag created as a byproduct of aileron inputs, which cause the nose to swing toward the outside of the turn, resulting in uncoordinated sideslip and inefficient turning of the aircraft.  In the case of a V or Swallow tail, ruddervators fulfill the function of both rudders and elevators and would be used to counter adverse yaw as well.