Step 5: Update: Resistors.
Due to popular community request, I have added a section about resistors and ohm's law.
First, resistors. Resistors are small electronic devices that limit current and/or voltage. (hence the name resistor) In "power sorce" I put a big, fat X over the 9v battery. That was wrong-ish. You can use a 9v IF and only if you have a resistor. "But what resistor should I use?" is a qestion I can hear through you computers. You have to use "Ohm's Law". Ohm's Law is a mathematical formula used to find resistence, voltage, or amperage. (it can also determen wattage, but that is a little complicated.) It states: R=V/A where "R" is resistance, "V" is voltage, and "A" is amerage. Using that, you will be able to find the proper resistor to use with you LED. (You have to do the math on your own, that way you learn)