you have to call a javascript routine. Use something like
this:
<html>
<head>
<script type="text/javascript">
function disable()
{
if (event.button == 2)
{
alert("Sorry no rightclick on this page.\nYou cannot view
my source\nand you cannot steal my images.")
}
}
</script>
</head>
<body onmousedown="disable()">
<p>Right-click on this page to trigger the event.</p>
<p>The event property is not recognized in Netscape.</p>
</body>
</html>