There are many ways to add music to your blog. The most common and easy way is to embed it into your blog and add it as a HTML/Javascript widget via the "Add a Gadget" in the Layout.Here I show you all how to add music as background on you blog..
You will first have to find a music file that is already hosted on the web, or if you have your own music file stored in your computer, upload it into a file host and then get the URL of the file. I actually always use geocities to get url for my favorite song..If not, you also can get the url from the mp3 hosting such as http://www.freemp3mail.com. You need select the artist the the song, then you will provided with the url for that song.
Click on Dashboard---Layout----ADD page Gadget-----HTML/javascript
Find this code in your template:
<script>
<!--
//specify FULL path to mp3
var musicsrc="http://your song.mp3"
if (navigator.appName=="Microsoft Internet Explorer")
document.write('<bgsound src='+'"'+musicsrc+'"'+' loop="infinite">')
else
document.write('<embed src=\"'+musicsrc+'\" hidden="true" border="0" width="20" height="20" autostart="true" loop="true">')
//-->
</script>
change that http://your song.mp3 with the url that you already upload or found over the Internet.
Just copy and paste the code in your HTML/JAVASCRIPT
Thats all there is to it!