та шо там не понятного. все оч легко:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN">
<html>
<head>
<meta charset="utf-8" />
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/smoothness/jquery-ui.css" />
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
<style type="text/css">
#slider
{
width: 200px;
margin: 40px;
}
</style>
<script>
$(function() {
var div = document.getElementsByTagName('div')[0];
$( "#slider" ).slider(
{
min: 0,
max: 100,
value: 100,
change: function(e, ui)
{
div.style.opacity = ui.value / 100;
}
});
});
</script>
</head>
<body>
<div style="height: 50px; width: 50px; background-color: red; opacity: 1;"></div>
<div id="slider"></div>
</body>
</html>