Work your way around the room marking the seam locations with a pencil. Cut the wallpaper using a straight edge and a utility knife. Allow it to soak for 15 seconds. Hold the wallpaper by the corners and slowly remove it, adhesive side out. Book the ends of the wallpaper by folding it over, adhesive side in, and matching up the corners.
Booking helps spread the adhesive evenly.
After about 2 minutes, peel the ends apart and apply the wallpaper to the wall. Work from the top down, aligning the edge with the vertical starting line. Use a wallpaper brush to smooth the paper and remove air bubbles. Brush from the top down and work from the center outward. Butt a second strip tightly against the first strip, and match the pattern.