Take a moment to consider where you'd like to attach the box. On my bike, I clamped it to the bike frame near the head tube. This way it's away from my knees and easily accessible.
Grab hold of the tabs and carefully pull them apart to widen the opening. Press the clip onto the framing of the bike (38mm / 1.5in diameter tubing). The clips should clamp onto framing. Insert a M3 x 10mm pan head machine screw through the hole in the tab. Use an M3 nylon lock nut to secure the clips. A socket wrench or pliers can assist in grasping onto the locknut while fastening. Repeat this process for the second clip.
Take a moment to consider where you'd like to attach the headlight. On my bike, I attached them to the lower part of the handlebars.
Following a similar process, pull the tabs apart from the headlight clips and clamp it onto the tubing. You might find it easier to do one clip at a time. Use another set of M3 x 10mm screws and M3 lock nuts to secure the clips onto the tubing.
And here's the final assembly! Take a moment to test out the placement of the clips by turning the handle bars, breaking, etc. Make sure the clips, headlight and box enclosure do not obstruct control of the bike – You're safety depends on this, so please consider it. I personally hit my knees a few times on the box enclosure because I placed it in the center of the frame.