Step 5: Wire it up (again)
Solder the appropriate wires depending on your circuit, whether you are using one or two switches and whether you include the LED. It's unwieldy to explain in writing so I'll just give the circuit diagrams- however you wire it up, the circuit board should have wires soldered to the battery terminals, charge switch terminals, shutter switch terminals and optionally the "ready" LED wire. Once you have the wires soldered on, tape the power wires to the battery (or put the battery in the holder), push the switch through the hole in the tin, screw the nuts on to secure it and settle the circuit into its new home.
Once you have the trigger wires at a comfortable length, add a strain relief on the inside. I prefer to tightly put a zip tie around the trigger wires, but you can just tie a knot in them at this point.