You've answered your own question - to a degree...
This is a little too involved to just explore it without some upfront work on your part.
If you just want something working, maybe you should go to the script request section.
If you've already started doing some of your work and have some questions, it would
then be appropriate to ask for help with that.
If you've already started playing around with the xml and need help with that, post the relevant code snippets.
On another note...
From just a design overview standpoint, these are some of the items you'll need for the app:
(this is basic and doesn't reflect all that you'll need)
Admin:
1- Database calls
2- Presentation
3- Upload song (manage songs i.e. rename, delete, etc.)
4- Read xml
5- Generate xml
User:
1- Database calls
2- Read xml
3- Presentation (display songs)
4- Get song
5- Play song