Locate an electrical outlet. Electrical boxes are positioned on the sides of wall studs; usually, you can find them an inch away.
Press a thumbtack into the base of the wall at regular intervals near the outlet plate on either side. If you meet resistance, you've hit the stud.
Run the stud finder horizontally along the wall and watch the indicator light or listen for the audio cue per the device's instruction manual. It will inform you when it detects a stud.
Measure 16 inches horizontally from the stud to get to the next stud. Mark its location.