I am perhaps a bit stupid but it took me a while to figure out how to get it working. I had enabled JCE as the default editor under Global Site Config but I had not disabled TinyMCE under Extensions/Plug-in Manager/Editors
Don't forget to do this and you won't waste time faffing about before this this great extension. Thought I would post as it might help other newbies :)
THANKS to the developer.
1.I had to enable mp3 content in Site Global Configuration.
2.Install. Then click on Extensions/plug in to enable.
3.Create article and then either insert full html:// or upload mp3 content from your computer to media manager/stories/ (create new mp3 folder).
Looks simple and it works - thanks to the developer.