Measure the garage door panel's length and divide it in half. Place a small mark on the panel's top edge at this location. Center a garage door hinge over the mark and secure it in place with a machine-thread lag screw.
Place one wheel hinge on the panel's right edge, along the top edge. Secure this hinge to the panel with machine-thread lag screws, and insert a wheel through the hinge's hole.
Carry the panel to the garage door opening. Insert the wheel into the track on the garage door opening's right side, and set the panel's bottom edge on the first panel's top edge.
Lift up the first panel's hinges, and mark the screw holes' locations onto the second panel. Drill a 1/8-inch pilot hole through the panel at each mark. Lift the hinges back up and drive machine-thread lag screws through the screw holes to hold the two panels together.
Insert a second wheel into a second wheel hinge. Insert the wheel into the track on the garage door opening's left side. Slide the hinge down into position on the panel's left edge, near the top edge. Secure the hinge to the panel with machine-thread lag screws.
Repeat steps 1 through 5 to add any remaining garage door panels in the garage door opening.