First grab a five gallon bucket and mix your drywall compound. I liked using the powdered wall texture because it was easier to mix to the right consistency and the leftovers store really well; however, according to the second tutorial you can use any type of drywall compound as long as you can get it to the right consistency (somewhere between the thickness of frosting and peanut butter).
After you've mixed your compound pour it into a paint tray and start rolling it on the walls. We used a plastic loop roller, which is exactly what it sounds like...a roller covered in tiny loops of plastics. We tried using a regular old paint roller too, but the results with the plastic loop roller were much better. Your goal is to create lots of peaks and valleys all over the walls so that when you come back and "knock-it-down" the wall doesn't become one big schmear of drywall mud.