One of the new rear cardboard pieces needs to be marked for punching holes.
Overlay the old cardboard on top of the new for best fit, then spray each hole with spray paint.
The new cardboard will have the holes marked in the correct position. Use a hammer and gasket hole puncher to cut out the holes.
The front curtain mat is similarly marked. You will need a sharp utility knife to cut out the rectangular holes.
The front trunk curtain is held onto the wall by metal tabs in the sheet metal.
The mats can be laid in place after the cardboard is installed.
Gray special pushpins hold the side and rear cardboard in place.
Install the small mat piece that covers the center trunk latch mount before installing the rear cardboard or the main bottom mat.
You will need to use some adhesive to keep in in place. 3M weatherstrip adhesive works well.