Sweep or vacuum the area to remove any dirt or debris.
Start against the wall and unroll one roll of the underlayment from one side of the wall to the other. Spread the underlayment up to the wall so that it touches the side wall and the walls at the front and back of the room. Notice that one side of the underlayment has a strip of adhesive. That side should be on the far side, so that the next piece of underlayment can stick to it.
Use a razor blade to cut the underlayment to fit. Slice the underlayment straight across, using the wall as the guide. The cut does not need to be prefect as long as the underlayment fits.
Line the next roll up to the roll that you just laid down and unroll it in the same fashion as you did before, including trimming it to fit.
Slide the second piece over slightly until it lines up with the adhesive strip on the first piece. Once they are lined up, peel away the paper on top of the strip and stick the two pieces together.
Continue laying out the underlayment, trimming it and attaching it to the previously laid piece, until the floor is completely covered with underlayment.
Begin your laminate installation. You do not need to allow the underlayment to settle; you can install the laminate immediately after you complete laying down the underlayment.