Stick the putty knife blade into the tub of spackling paste and dig out enough to cover the bottom inch of the knife.
Smooth the spackling paste over the screw holes and work it into the holes. Use the knife at a low angle to the wall's surface to smooth the paste. Completely fill the holes with the spackling paste. Allow the paste to dry for 24 hours so it can completely harden.
Sand areas where the spackling paste was applied, using a drywall sanding sponge. Make the surface as smooth as you can. Apply a second coat of spackling to fill depressed areas around the screw holes. Allow the second coat to dry and sand again. Clean with a tack cloth.
Paint the repaired area with a 2-inch paintbrush and paint that matches the rest of the wall.