How to customise a flatpack wardrobe
Take the insert and line it up against the pre-drilled screw holes on the outside of your drawer and screw it on. Take the other drawer runner and repeat this process on the other side of the drawer.
Line up the drawer guide part of the runner with the pre-drilled screw holes on the inside of the drawer cabinet. Screw the drawer guide into place. Then do the same on the opposite side of the cabinet.