Begin by measuring the space, to determine what size countertop needs to be installed. When measuring, take into account the size of the backsplash, and how much room you will need to leave for it. You will have to buy a slab of quartz countertop either to the same size of the area, or a little larger that can be cut down. If you find one that needs to be trimmed or cut, mark where to cut on the quartz with painter's tape.