Step 4: Assembling the electronics box
Drill some holes on the end, clean up the sharp edges, and insert some rubber grommets. Insert the AC power cable, tie a knot in it to prevent it from slipping, and solder it to the circuit board. Make sure that the live and neutral wires are hooked to the right place. I had to check which wire was which on my multimeter--the "fat" prong on the plug side goes to neutral while the thin prong goes to hot/live. Also make sure to get a very solid soldered connection--you don't want this coming undone! The GFCI will help if anything goes seriously wrong, but you don't want to get to that point.
You'll need three wires for the other side--one for ground, one for LED positive, and one for the fan positive. Insert the wires through the grommet and tie another knot.
I don't have a picture here, but for the interior connection you'll want ground to go to the black wire from the board, of course, as well as LED positive to red. For the fan wire (yellow, here), you'll want to tie it to a reasonably beefy resistor (2 watt, 470 ohm is good). The other side of the resistor goes to the normal positive lead. Make sure to shrink-wrap everything.
When you finally test this, make sure to wear safety glasses the first time and stand back a ways. Nothing should go wrong if you've been careful, but in the worst case a component could explode and send shrapnel out. Be careful, and as before ASK FOR HELP if you aren't sure about the wiring. AC wall power is nothing to play around with.
I used Kapton double-sided tape to attach the board to the case, but you may want something more robust. The board had a large metal plate on the bottom that you can tap and screw into if you like. I may just go that myself, but for now the tape is sufficient (Kapton is strong and heat-resistant).
By the way, this circuit board handles any input voltage from 85 to 265, so it will work equally well anywhere in the world if you have the right plug.