Place board

Identify the bottom case and note the "in" and "out" text. Align the USB Plug to the retainer and the "out" text on the case.

Apply a small amount of pressure to press fit the PCB into the bottom case.

Snap fit case

Place the "in" and "out" text to match the plug and socket on the board. Align the top case to the snap fit nubs on one side of the bottom case. Place one side of the case over the nubs and the then use a small amount of force to join the two halves together.