Assemble the door tracks. The precise method can vary by manufacturer, so follow the instructions.
Install the rollers and any needed brackets on the bottom door section, following the manufacturer's instructions. Move the panel into the doorway, centering it.
Slide the tracks over the wheels on the door panel, leaving a small amount of space between the panel and the tracks so movement isn't restricted.
Drive screws partway through the holes on the tracks and into the framing. Don't drive the screws completely into the framing yet in case you need to adjust the tracks.
Connect the hinge and roller to one side of the second door panel.
Place the second door panel on top of the first panel, sliding the wheel into the track as you do it.
Attach the wheel to the other side of the second door panel.
Check the tracks for level and make sure they're not too tight against the door, and screw them tightly into the door frame.