The QR code is a black-and-white box that appears on a printed illustration. If you hover over the QR code, you'll see identifying information appear, including: the title of the experiment, the name of the illustration (that was given when the illustration was saved), and the URL of the page that generated the illustration.  You can take the picture of a QR code with your iphone or blackberry to get the URL of the illustration.  The quickmark iphone app has worked well for doing this.