When you're putting up shelves or hanging large pictures or mirrors on a wall, it's important to drive the nails or screws into wall studs. The challenge is finding those studs. If you don't have an electronic stud finder, you can locate studs with nothing more than a table lamp. Remove the shade, turn on the lamp and hold the bare bulb 10 to 12 inches away from the wall. Look for the silhouettes of nailheads or drywall tape as the side light skims the surface of the wall; you should find a stud directly behind the nailheads or tape. Then look for other studs spaced either 16 or 24 inches on center.