Measure across from one garage door rail to the other then double the number to account for the height of the rails. Measure the length of the garage door rails, plus an additional 3 feet on either side. Write down the numbers for future reference.
Cut a piece of fabric of the dimensions noted in Step 1. Select a thicker fabric, such as velvet or canvas, for added durability in the garage environment.
Remove any vehicles or items from the garage and spread the fabric out underneath the garage door rail setup. Line up the fabric so the orientation matches that of the rails.
Pick up one corner of the fabric and use a staple gun to attach it to the ceiling above one of the garage door rails. Repeat this process to attach the fabric in all four corners.
Staple the fabric to the ceiling around the perimeters of the garage door rails to complete the installation.