Sound "FadeOut" via ActionScript


I have a sound object in my movie called ‘muzik’
How Could I make that sound to “Fade Out” on some event?
I do not know Action Script well yet, so I don’t know how to write such script.

I think I should do something like that :

step = 1;
do {
_leve1.muzik.setVolume(_leve1.muzik._Volume - step);

} while (_leve1.muzik._Volume > 0);

The problem is that the object “muzik” doesn’t have such a property “_Volume”.

So that’s the point. Could somebody help me with this, please?

thank you.