The Processing examples use ArtBus to interact with images, sound, and the Internet. Hookup diagrams for digital and analog input, and digital output show how to make the basic hardware connections.
You will need these. It's good to open the diagrams in separate browser tabs:
It should all just plug-n-play, but keep a couple of things in mind.
The letter A is the address. You need to change this to the letter you got when your board printed its address. If it said "Hi from G..." cahnge the line of example code to read: port.write("!Ga1;");
Here are the basic commands for the analog board and the digital board.