HELP... Were is the reverse switch? Or ground for the tail light reverse?

Hay all, just installing a reverse camera to the Supra.

I need to know were I can put a wire to the reverse switch so when the car is put into reverse the back up camera will turn on but I don't know were to it?

Or even the tail reverse light which one would be ground?

Can ant one help?

Thanks

Paul

All sorted now peps. The wire needed to be connected to a reverse positive. So connected it to the rear light reverse loom were it had been cut off for a fog light conversion. Works a treat