Blink an LED using the Raspberry Pi's GPIO Pins
All below are connected in series: GPIO Pin 7 (3.3V) -> Positive end of LED Negative LED -> 1kohm current limit resistor 1kohm -> GPIO Pin 6 (GND)
http://elegantcircuits.com/2014/08/18/using-the-raspberry-pis-gpio-pins-to-drive-an-led/