First you need to connect your LED to the battery.

You'll want only a short distance between the LED and the coin cell holder, so first of all cut the wires to the desired length (in our case, about 4cm) and strip the ends bare.

Twist the ends of the wires around the legs of the LEDs, paying attention to their polarity; the long leg of the LED needs to connect to the red wire, the short leg of the LED connects to the black wire.

Make sure the LED turns on and then seal the connection between the LED legs and wires with solder.

Remember to remove the battery before exposing the coin cell holder to heat in the next step.