Audio Tracks

I am new at Digital Video Editing and I am wondering about including optional audio tracks. I would like to include in my home videos a narrative track that can be turned on or off ie. I would like to be able to hear the original audio or the narrative audio when watching the video off the DVD. I understand how to incoropate different audio tracks I just can't figure out how to allow the DVD viewer to select one track or the other. Sorry if this has already been covered and thanks for your time.