Purchase a high-quality filler from a hardware or home improvement store. Choose the type of filler based on the door and frame material. Select an auto-body filler for metal doors or frames and a wood putty for wooden doors or frames.
Sand the ding and the surrounding area to remove any paint or roughness from the surface. Wipe the area clean with a damp cloth and allow it to dry.
Apply the auto-body filler or wood putty, filling in the dented area of the door or frame. Press the material firmly into the area. Wipe off any excess filling with the putty knife so the filled area is flush with the frame or door.
Allow the filling to dry and cure thoroughly, then sand it lightly with fine sandpaper until smooth. Use a sanding block or sandpaper attached to a block of wood to keep the repaired area flush with the rest of the surface.
Repaint wooden doors and frames with a high quality house paint or stain the repaired area to match the woodwork. Before repainting metal doors or frames, it is essential to apply a rust inhibiting primer to prevent the repaired area from rusting.