Here you go:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Untitled Document</title>
<style type="text/css">
/*Credits: Dynamic Drive CSS Library */
/*URL: http://www.dynamicdrive.com/style/ */
.sidebarmenu {
float: right; /*The floats the entire menu to the right, you can remove this when you place it on your site*/
}
.sidebarmenu ul {
margin: 0;
padding: 0;
list-style-type: none;
font: bold 13px Verdana;
width: 180px; /* Main Menu Item widths */
border-bottom: 1px solid #ccc;
text-align: right;
}
.sidebarmenu ul li {
position: relative;
}
/* Top level menu links style */
.sidebarmenu ul li a {
display: block;
overflow: auto; /*force hasLayout in IE7 */
color: white;
text-decoration: none;
padding: 6px;
border-bottom: 1px solid #778;
border-right: 1px solid #778;
}
.sidebarmenu ul li a:link, .sidebarmenu ul li a:visited, .sidebarmenu ul li a:active {
background-color: #012D58; /*background of tabs (default state)*/
}
.sidebarmenu ul li a:visited {
color: white;
}
.sidebarmenu ul li a:hover {
background-color: black;
}
/*Sub level menu items */
.sidebarmenu ul li ul {
position: absolute;
width: 170px; /*Sub Menu Items width */
top: 0;
visibility: hidden;
}
.sidebarmenu a.subfolderstyle {
background: url(right.gif) no-repeat 3% 50%;
}
/* Holly Hack for IE \*/
* html .sidebarmenu ul li {
float: left;
height: 1%;
}
* html .sidebarmenu ul li a {
height: 1%;
}
/* End */
</style>
<script type="text/javascript">
//Nested Side Bar Menu (Mar 20th, 09)
//By Dynamic Drive: http://www.dynamicdrive.com/style/
var menuids=["sidebarmenu1"] //Enter id(s) of each Side Bar Menu's main UL, separated by commas
function initsidebarmenu(){
for (var i=0; i<menuids.length; i++){
var ultags=document.getElementById(menuids[i]).getElementsByTagName("ul")
for (var t=0; t<ultags.length; t++){
ultags[t].parentNode.getElementsByTagName("a")[0].className+=" subfolderstyle"
if (ultags[t].parentNode.parentNode.id==menuids[i]) //if this is a first level submenu
ultags[t].style.right=ultags[t].parentNode.offsetWidth+"px" //dynamically position first level submenus to be width of main menu item
else //else if this is a sub level submenu (ul)
ultags[t].style.right=ultags[t-1].getElementsByTagName("a")[0].offsetWidth+"px" //position menu to the right of menu item that activated it
ultags[t].parentNode.onmouseover=function(){
this.getElementsByTagName("ul")[0].style.display="block"
}
ultags[t].parentNode.onmouseout=function(){
this.getElementsByTagName("ul")[0].style.display="none"
}
}
for (var t=ultags.length-1; t>-1; t--){ //loop through all sub menus again, and use "display:none" to hide menus (to prevent possible page scrollbars
ultags[t].style.visibility="visible"
ultags[t].style.display="none"
}
}
}
if (window.addEventListener)
window.addEventListener("load", initsidebarmenu, false)
else if (window.attachEvent)
window.attachEvent("onload", initsidebarmenu)
</script>
</head>
<body>
<div class="sidebarmenu">
<ul id="sidebarmenu1">
<li><a href="#">Item 1</a></li>
<li><a href="#">Item 2</a></li>
<li><a href="#">Folder 1</a>
<ul>
<li><a href="#">Sub Item 1.1</a></li>
<li><a href="#">Sub Item 1.2</a></li>
</ul>
</li>
<li><a href="#">Item 3</a></li>
<li><a href="#">Folder 2</a>
<ul>
<li><a href="#">Sub Item 2.1</a></li>
<li><a href="#">Folder 2.1</a>
<ul>
<li><a href="#">Sub Item 2.1.1</a></li>
<li><a href="#">Sub Item 2.1.2</a></li>
<li><a href="#">Sub Item 2.1.3</a></li>
<li><a href="#">Sub Item 2.1.4</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#">Item 4</a></li>
</ul>
</div>
</body>
</html>
All you need to do is change the arrow image to one that points to the left.
Good luck!