This is a re-publish so that I can put it in a contest and edit. This is in the green contest because you are re-using an old battery.
Step 1: Step 1
Step 2: Step 2
Step 4: TaDa!!
The LED should light up. If it doesn't, switch the connections. Both LED's will light up and you will have a flashlight or light. Enjoy.
It provides ~5v so you could also use this for a USB charger, or IR light.
Post anything else you think is needed.