Fill a large plastic bucket with ready-mix drywall compound and water as instructed on the packaging. To achieve the correct consistency, be sure to follow the instructed ratio of water to compound precisely.
Allow the drywall compound to settle for 10 to 12 minutes, then stir the mixture briefly to re-integrate the materials.
Scoop up the compound onto the end of a drywall knife and hold the knife at a 45 degree angle to the drywall as you scrape the compound over the damage in a downward stroke. Make short strokes with the putty knife until the hole has been filled with the compound and is level with the existing wall.
Wait five minutes for the compound to dry and then run a damp cloth over the compound gently. Remove any misapplied compound surrounding the repair with the cloth. Follow the curing time listed on the compound's label before painting or sealing the repair.