Double the measured width of the door opening to determine the needed length of the track.
Cut the track to the length needed using a hacksaw or reciprocating saw equipped with a metal cutting blade.
Determine the mounting style of the track. It will either mount with clips that come with the track kit or by screwing through tabs that are welded to the top of the track. If clips are used, simply slide them on the track from the ends and space them evenly.
Mount the track to the wall, using the supplied screws, with the bottom of the track three inches above the top of the door opening. Make sure the track is level. Choose which side of the opening the door will slide and mount the track flush with the other side.
Lay the door face down and place the rollers one to two inches below the upper edge of the door. Start with by placing rollers six inches in from each side and distribute the rest evenly between them.
Use a pencil to mark the screw holes and remove the rollers. Bore a hole through the door at each mark, using a drill bit that is as wide as the screw holes.
Insert the carriage bolts that came with the rollers from the front side of the door and through the rollers on the back side of the door. Fasten using the supplied washers and nuts.