On one side of your base cabinet, measure and mark out where you will be drilling the holes to attach the drawer runners and the lid holder. You’ll find these measurements in the instruction book that comes with your kit.
Use a spirit level to draw lines from the back of the cabinet to the front, so that you know the holes you’re drilling are in a straight line. Once you marked where you need to drill, pre-drill the holes using a small drill bit. Repeat this process for the other side.