Lightning mcqueen tv and dvd set-up, won't play, have direct tv hook-up

I have a lightning mcqueen 13' tv model# C1310ATV, and a little purple car-DVD player model # C8000 for my grandson, I cannot get dvd to play on tv? Should I hook it up(dvd) to back of tv or the front of tv, and if so, is there a switch over button for dvd to normal tv watching. TV is hooked up to Direct tv and plays fine. But can't get dvd to play on tv, I've tryed channels 2, 3, and 4. But no picture. Again is there a switch over button or auxiliary button or ???

Your help and consideration, concerning this problem will be greatly appreciated by my grandson and myself.

This is my 3rd request, I assume no help is available.

Thanks