If you purchased the kit that includes all parts, a y splitter would be included. I believe the power packs include one as well. You plug one into the receiver and the aileron servos plug in to the other end.
An alternative, if you have a 6-channel receiver and transmitter, is to plug one aileron into the aileron channel and the other into channel 6 and set your radio for Dual Aileron mode. What kind of radio and receiver do you have?
Also note, that if you use a Y cable... when you build the plane make sure the wires coming out of the servos BOTH go either towards the front or back of the plane. That way, one will go up, while the other goes down...
(Ask me how I learned that little tidbit!)