The problem you're having is that the event-handlers are being bound before the elements are present in the DOM, if you wrap the jQuery inside of a $(document).ready() then it should work perfectly well:
$(document).ready(
function(){
$("#music").click(function () {
$("#musicinfo").show("slow");
});
});
An alternative is to place the <script></script> at the foot of the page, so it's encountered after the DOM has been loaded and ready.
To make the div hide again, once the #music element is clicked, simply use toggle():
$(document).ready(
function(){
$("#music").click(function () {
$("#musicinfo").toggle();
});
});
And for fading:
$(document).ready(
function(){
$("#music").click(function () {
$("#musicinfo").fadeToggle();
});
});