Cut the track with a hacksaw. Cut it to match the exact size of the door.
Position the track in the middle of the frame header. Tighten the screws in the pre-drilled holes into the studs.
Slide the two trolley hangers -- also called rollers -- into the end of the track.
Position the hanger brackets on the top of the door. Center the brackets and place them between about 2 1/2 inches from each end.
Slide the hangers until they line up with the position of the hanger brackets.
Lift the door. Slide the hanger into the screw opening on the hanger bracket. Adjust the screws at the bottom of the trolley, if necessary. Release the door.