The spacers need to be screwed on the inside of the cupboard at either end, so you can attach the runners to them. The first spacer to attach has pre-drilled holes in a straight line. If you’re unsure, check the instructions. Turn the cabinet onto its end and use a drill to fasten the spacer to its side. Make sure the laminated, white edge is pointing to the front of the cabinet. Place the other spacer on top of the first and use a drill and screws to fix it in place. Repeat this process at the other end of the cupboard.