Remove the shower rod and its end brackets from the walls, if applicable.
Scrape the blade of a putty knife or a piece of sandpaper across the wall surface over the screw holes to remove any small, loose pieces of drywall.
Apply a small dollop of lightweight filler putty to the wall surface using a putty knife, pulling the putty across the drywall surface at the screw holes to fill them. Repeat the application until each of the holes has been filled with putty.
Allow the lightweight filler putty to cure for 10 to 15 minutes, until it's dried completely.
Sand over the filled screw holes with sandpaper or sand block or pad to flush the wall surface and complete the patch for painting.