Steps:1. Insert vent cover in hole and drill two small locator holes in drywall and vent cover (figure A). Be sure to wear safety glasses.
2. Remove cover, switch to larger drill bit (about 3/16-of an inch) and go back in the locator holes and drill holes to fit drywall anchors (figure B).
3. Insert anchors by hand and tap in gently with hammer until flush with ceiling surface (figure C). Take care not to break the drywall.
4. Take the power drill and enlarge the mounting holes in the vent cover before mounting (figure D).
5. Place vent cover back over hole. Insert screws by hand using Phillips-head screwdriver.
6. Keep the dust down by cleaning vent covers regularly with an old toothbrush (figure E).