Horizontal rope chop help

Raegold

I'm doing the Strong Curves program, and I'm having some trouble with the horizontal rope chop... I think I may have gotten the movement down, but where exactly should I be feeling this? Should I be squeezing the glute on that side when I twist? In the book, Bret says to twist from the upper back and hips, not lumbar spine... I'm just a little confused if I'm doing it right. I did one set and then just did pallof presses bc I wasn't sure.