Since no-one more knowledgeable has replied . . .
You could do worse than look at this Ubuntu guide:
http://ubuntuforums.org/showthread.php?t=205449
and follow the general approach.
Of course,
apt-get is for Debian- based distros, use
yum instead if you have to.
One thing they don't mention that had me stumped:you may find that sound works when the Alsa widget shows MUTED if you are not using IEC9588 (Linux-speak for S/PDIF ie digital) I don't know what you have for speakers, but if they are hooked up with an audio cable this may be it. Also check that you are in the audio group.