Place the square of aluminum foil on the floor, directly under the area of wall on which you are working. Gently sand the scraped area of paint to remove any flaky edges, and vacuum the wall using the small brush attachment to remove all sanding dust.
Place a little spackling paste in the scraped area and use the filler knife to spread it. Once the scrape is filled, remove any excess spackling paste with the filler knife, and allow the repair to dry. Gently sand the dry spackling paste completely level with the rest of the wall.
Vacuum the area again, using the small brush attachment to remove all the sanding dust. Wash the area concerned with the damp sponge to remove all traces of dirt. Allow the wall to dry thoroughly.
Apply paint to the scrape using a small paintbrush. Spread the paint out to blend it in with the existing paint as much as possible. Allow the paint to dry. If the scraped area looks lighter than the surrounding wall, apply a second coat of paint in exactly the same way.