Use jQuery.
The syntax would be as easy as the following:
$('#myHeading').click(function(){
// Your code here
});
Sometimes with ASP.NET I have had to use a wildcard ID match because ASP.NET creates really long semi-random clientside ID's for your elements. You would do something like the following:
$('[id*="myHeading"]').click(function(){
// Your code here
});
Essentially you can select anything on the DOM and attach an event handler to it with jQuery. Sometimes you have to get creative with the selectors.
IMPORTANT: If you are using updatepanels and the heading you want to monitor for a click is inside that panel, you will need to REBIND those event handlers to the element you are selecting after the panel is loaded/re-loaded via ajax. This can be achieved using the following code:
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_pageLoaded(panelLoaded);
function panelLoaded(sender, args){
$('[id*="myHeading"]').click(function(){
// Do something after there is a click
});
}