Measure the length of the window arches to determine the necessary rod lengths.
Cut the flexible tracks to the determined lengths, using a hacksaw. Place the end cap over the cut end.
Place pencil marks at the bottom centers of the window side jambs, where the ends of the curtain rods will sit.
Drill pilot holes at the marks, using a drill bit with a diameter slightly smaller than the threads of the curtain track mounting bracket screws.
Drill pilot holes and screw additional, evenly spaced brackets, as recommended by the track manufacturer.
Snap the ends of tracks into the first brackets. Bend the tracks to the shape of the arches, snapping them into the subsequent brackets along the way until reaching the last brackets.
Snap the curtain hooks onto the tracks.