How do I use it?

Well, that's mostly up to you! There are a few things I will point out, though:

Using the LEDs

As the assembly guide points out, you have to wire the LEDs to whichever Arduino

pin you'd like. Once you've done that, you can program your Arduino to run the ever-

important 'Blink' sketch (in Arduino, go to File->Examples->Digital->Blink):