1. Measure the wall size before purchasing. Sand down rough surfaces prior to sticking. Check and clean the walls to make sure they are dry and smooth. Cut the appropriate wallpaper according to the measured size, leaving about 5mm extra overlap on all edges is better. Peel the back paper then stick to the smooth surface from top to bottom, from the center to edges it's better to use a soft cloth to smooth out. If there are air bubbles after pasting the contact paper, you can pierce a hole with a needle or a knife to chasing away bubbles.