Scrape the surface of a hole in the Sheetrock with the putty knife to remove any loose material. You can also push the material into the hole.
Remove the lid from the container of Spackle and scoop out a small amount with the putty knife.
Place the putty knife over the hole and press down. Slide the putty knife down to force the Spackle into the hole. Repeat this process until Spackle will no longer fill the hole.
Smooth the Spackle by scraping the putty knife over the hole. Scrape off any excess Spackle around the hole, as needed, until it is nearly flush with the surface.
Place the lid back on the container of Spackle. Allow four to eight hours for the Spackle to sufficiently dry.
Sand the Spackle lightly with the sandpaper until the surface of the Sheetrock is smooth.