Laying carpet underlay is easy, its just a matter of removing the existing floor covering - all of it and giving the floor a good brush. Then rolling out your new carpet underlay and cutting with a sharp blade. Don't overlap the edges. Leave a few centermetres between the underlay and the skirtings, to give the carpet a bit of space to fit. Also, you may want to use this space to run wiring, such as telephone cable. The video below is just a bit of fun, however, do ensure nothing is left on top of the underlay when you put the carpet in!