Use the painter's tape to tape off baseboards, window sills, electricity covers and other areas of the room that you want to protect from being primed or painted.
Pry open the lid of the primer with a screwdriver or flat knife tool.
Stir the primer. Use the paint mixing stick to stir the primer in the can.
Pour some of the primer into the paint pan.
Dip your paint brush into the primer. Use the paint brush to apply the primer to the corners of the walls and along the edge on the top, where the wall meets the ceiling, and along the bottom where the wall meets the baseboard. Apply the primer out approximately an inch from the edge of each wall because this is the area that the paint rolling brush will not be able to reach.
Roll the paint roller brush in the "bowl" of the paint pan. Turn the roller in the primer so that all sides of the roller have a coat of primer on it.
Apply the primer to the wall. Apply the primer to the wall by rolling the paint roller brush up and down. Reapply primer and repeat until the walls are a whitewashed and the old bright paint color is completely covered.
Allow the primer to dry according to the directions on the can. Drying times can vary according to the climate of the region and the temperature in the home where you are painting. Once the primer is dry you can then prepare the walls to apply the new lighter color than the original bright paint. Preparation can include filling in holes and using sandpaper to smooth out rough spots on the walls. Then you can apply the new paint color.