What do I have to do if I want to use the lengthways single bed extension for the first time?

You must remove the protective cover from the existing upholstery and remove the upholstery core. You then insert the upholstered core into the new cover. To do this, you must insert the upholstered core into the rear, larger area of the bed expander (upholstered cover). The bed expander is now ready for use.