Create a page to put your Audio file on (I use the In the Media pre-fab page)
Then select an Item to make it a link, example Item 2
click on the Edit/Create Link tab at top (looks like a chain link)
Click on Attachment in the links menu
Click on Choose File and select the file you want to use, example mymusic.mp3
Then click on the OK button at the top
Publish your website
That should do it.
