OClean all the room - get gone obstacles, probably by putting all furniture on either side of the room then put old newspapers to protect the floorboards. Although you're interested to know how to color over wallpaper, staining ground is probably the last thing you were going to do. https://howtoremovepaintfromwalls48158.blogoscience.com/37821711/indicators-on-how-to-remove-paint-from-walls-you-should-know