rear wiper

I feel really dumb, but I have to fill my rear washer fluid and cannot seem to find where it is. I have a 93 Plymouth Voyager. I did see it a while back but never needed to fill it. Now the winter has finally come and I have none left for the rear window and need to refill. Thanks to anyone who can help with my silly question.

Open rear hatch, see the black thing with the plastic lid above the brake light on driver's side?

Thanks very much. I knew I saw it somewhere. Thanks again.