How can I use this API for project

Hi,

I'm a student, I am learning at Academy of Art University in Web Design and
New Media. I keep to find a function which can collect decibel data basic
html5 since last summer. Now I found the realtime analyser (link:
http://chromium.googlecode.com/svn/trunk/samples/audio/visualizer-gl.html)
is useful to me. But I am no idea how to use this API for my project,
because I want to learn the principle of this function, then using for my
project. It's awesome. Could you give me some suggestion.

Thank you very much

Best

Oliver