One photo with headliner installed showing the hook at the upper area of the quarter window. The other is with the headliner removed. The little bracket is where the hook attaches. I don't remember, but it looks like it takes a long screw as the bracket only positions the hook. The screw appears to go into the roof line structure.
You should be able to feel the bracket by running your hand across that headliner area. That bracket just snaps into the roof line structure.