Simple volume slider

I have made small site:

http://www.um-design.com/test/Untitled-1.html

But I can manage to work my on/oof music button with my slider.

Can somebody give me the most simple codes for this? I have already song inside the project, so it doesn’t need to be loaded from the web.

I have try everything, but nothing. I manage to turn on/off music, but to slide it… noup… :-/