can you explain a little more about how you want your site to work? do you just want a single mp3 player on your page playing some background music? or are you looking to build a site that will allow you ( and possibly others ) to upload music and have your web site visitors listen to the music? ( similar to youtube.com but for music instead of videos )
If it's the first, all you need to do is upload the player to your site, modify the dnn 'skin' you're using to include the javascript and place the player using the object or embed tag to position the player where you want it with the parameters you want.
If it's the second, look at the Repository module. You can modify the 'nifty video' template and replace the object and embed tags which embed the video player to instead embed the mp3 player. Then you can use that new template to allow music uploads and your visitors will be able to listen, search, rate and comment on the mp3s.
So, if your goal is one of those two designs, you can accomplish exactly what you need without having to spend any money buying 3rd party modules or having to look at any source code. If you need more help, just ask.