When the elevons are both up or both down they act like elevators. With both up, the nose of the airplane goes up and the aircraft climbs. With both down, the nose of the airplane goes down and the aircraft dives or descends.
When the elevons go up and down opposite of each other they act like ailerons. Left elevon up and right elevon down -- aircraft rolls to the left. Left elevon down and right elevon up -- aircraft rolls to the right.
On your transmitter, you would use the aileron stick to use the elevons separately and use the elevator stick to control them in unison.
