Download the example sketch from our Github repository:
Connect a LED to IOA and IOB as follows:
Cathode (short leg) of LED connected to the GPIO pin.
Anode (long leg) of LED connected to one end of a resistor*.
- Other end of the resistor connected to 5v.
* A 1K resistor is shown here as a 'safe' value. For maximum LED brightness, you can learn how to calculate the optimum resistance in this guide: http://learn.adafruit.com/all-about-leds