to set your linear drain you must first determine the finished floor height, then you need to set the drain at a height that will give you a 1-2% slope so that the water drains toward the drain. Then using the adjustable legs provided set the drain level making sure that it is also square to the shower area. once you are happy with its position you can screed the shower area creating the necessary sloped floor along the way. Then tank the area before installing your floor finishing.