obviously -you put red to red /black to black . BUT if the colors are not the same of the hitec to the extensions you have got , then you should get a multimeter or even some means of continueity , don't have the battery connected just plug the servo end & the extension end together & check on the end of exten; that the red wire from the servo will be the same as end going into the receiver . A multimeter is a must when messing with electrical stuff