Squeeze the handle trigger of the gun until the rivet attaches. Put pressure on the rivet as you squeeze the handle. Every squeeze will pull the metal pin in the rivet through the body. Once the pin's head reaches the small end of the rivet, it will begin compressing the 2 metal pieces together.

Push the head of the rivet through the holes in the sheets of metal. Make sure that the rivet comes through both sheets of metal at once (you may wish to look underneath and check), and is not impeded. Push down, and pull the handle of the rivet gun until you feel resistance.

Firmly grip the rivet gun: Hold the rivet gun handles firmly to retain control during the process. Squeeze the handles together: To engage the rivet gun, apply consistent pressure to the handles. Deform the rivet: As you squeeze the rivet gun’s handles, pressure is applied to the rivet, forcing it to deform and form a tight joint.

Insert the body of the pop rivet all the way into the pre-drilled hole. The flange of the rivet should be flush with the joint. Squeeze the trigger of the power rivet gun (or apply pressure to the levers on the manual rivet gun) until you hear the snap sound that indicates the mandrel has been removed.