body {
margin: 0;
padding: 0;
font-family: Arial, sans-serif;
font-size: 14px;
line-height: 150%;
background: #eee;
position: relative;
height: 100%;
}
.headerContainer,
.bodyContainer,
.footerContainer {
max-width: 960px;
margin: 0 auto;
background: #FFF;
}
.padding {
padding: 20px;
}
.bodyContainer {
min-height: 500px;
}
a.back-to-top {
display: none;
width: 60px;
height: 60px;
text-indent: -9999px;
position: fixed;
z-index: 999;
right: 20px;
bottom: 20px;
background: #62cc3e url("up-arrow.png") no-repeat center 43%;
-webkit-border-radius: 30px;
-moz-border-radius: 30px;
border-radius: 30px;
}
a:hover.back-to-top {
background-color: #000;
}

<link rel="stylesheet" href="css/back-to-top.css">

<a class="link-text back-to-top" href="#">Linked Text</a>

// change the value with how many pixels scrolled down the button will appear
var amountScrolled = 200;

$(window).scroll(function() {
if ($(window).scrollTop() > amountScrolled) {
$('a.back-to-top').fadeIn('slow');
} else {
$('a.back-to-top').fadeOut('slow');
}
});

$('a.back-to-top, a.simple-back-to-top').click(function() {
$('body, html').animate({
scrollTop: 0
}, 'slow');
return false;
});
</script>

<style>
a.back-to-top {
outline: 0;
display: none;
width: 60px;
height: 60px;
text-indent: -9999px;
position: fixed;
z-index: 999;
right: 20px;
bottom: 20px;
background: #000000 url("up-arrow.png") no-repeat center 43%;
opacity: 1.0;
-webkit-border-radius: 0px;
-moz-border-radius: 0px;
border-radius: 0px;
}
</style>
<script type="text/javascript">
$('body').prepend('<a href="#" class="back-to-top">Back to Top</a>');
</script>
<a href="#" class="back-to-top">Back to Top</a>

<script type="text/Javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script>
var amountScrolled = 100;

$(window).scroll(function() {
if ( $(window).scrollTop() > amountScrolled ) {
$('a.back-to-top').fadeIn('slow');
} else {
$('a.back-to-top').fadeOut('slow');
}
});
</script>
<script>
$('a.back-to-top').click(function() {
$('html, body').animate({
scrollTop: 0
}, 700);
return false;
});
</script>