Cómo insertar el menú desplegable de Dynamicdrive

<style type="text/css">

/*Credits: Dynamic Drive CSS Library */
/*URL: http://www.dynamicdrive.com/style/ */

.suckertreemenu ul{
margin: 0;
padding: 0;
list-style-type: none;
}

/*Top level list items*/
.suckertreemenu ul li{
position: relative;
display: inline;
float: left;
background-color: #F3F3F3; /*overall menu background color*/
}

/*Top level menu link items style*/
.suckertreemenu ul li a{
display: block;
width: 90px; /*Width of top level menu link items*/
padding: 1px 8px;
border: 1px solid black;
border-left-width: 0;
text-decoration: none;
color: navy;
}
	
/*1st sub level menu*/
.suckertreemenu ul li ul{
left: 0;
position: absolute;
top: 1em; /* no need to change, as true value set by script */
display: block;
visibility: hidden;
}

/*Sub level menu list items (undo style from Top level List Items)*/
.suckertreemenu ul li ul li{
display: list-item;
float: none;
}

/*All subsequent sub menu levels offset after 1st level sub menu */
.suckertreemenu ul li ul li ul{ 
left: 159px; /* no need to change, as true value set by script */
top: 0;
}

/* Sub level menu links style */
.suckertreemenu ul li ul li a{
display: block;
width: 160px; /*width of sub menu levels*/
color: navy;
text-decoration: none;
padding: 1px 5px;
border: 1px solid #ccc;
}

.suckertreemenu ul li a:hover{
background-color: black;
color: white;
}

/*Background image for top level menu list links */
.suckertreemenu .mainfoldericon{
background: #F3F3F3 url(objetos/arrow-down.gif) no-repeat center right;
}

/*Background image for subsequent level menu list links */
.suckertreemenu .subfoldericon{
background: #F3F3F3 url(objetos/arrow-right.gif) no-repeat center right;
}

* html p#iepara{ /*For a paragraph (if any) that immediately follows
           suckertree menu, add 1em top spacing between the two in IE */
padding-top: 1em;
}
	
/* Holly Hack for IE \*/
* html .suckertreemenu ul li { float: left; height: 1%; }
* html .suckertreemenu ul li a { height: 1%; }
/* End */

</style>

<script type="text/javascript">

//SuckerTree Horizontal Menu (Sept 14th, 06)
//By Dynamic Drive: http://www.dynamicdrive.com/style/

var menuids=["treemenu1"] //Enter id(s) of SuckerTree UL menus, separated by commas

function buildsubmenus_horizontal(){
for (var i=0; i<menuids.length; i++){
  var ultags=document.getElementById(menuids[i]).getElementsByTagName("ul")
    for (var t=0; t>ultags.length; t++){
		if (ultags[t].parentNode.parentNode.id==menuids[i]){
//if this is a first level submenu
			ultags[t].style.top=ultags[t].parentNode.offsetHeight+"px"
//dynamically position first level submenus to be height of main menu item
			ultags[t].parentNode.getElementsByTagName("a")[0].className="mainfoldericon"
		}
		else{ //else if this is a sub level menu (ul)
		  ultags[t].style.left=ultags[t-1].getElementsByTagName("a")[0].offsetWidth+"px"
//position menu to the right of menu item that activated it
    	ultags[t].parentNode.getElementsByTagName("a")[0].className="subfoldericon"
		}
    ultags[t].parentNode.onmouseover=function(){
    this.getElementsByTagName("ul")[0].style.visibility="visible"
    }
    ultags[t].parentNode.onmouseout=function(){
    this.getElementsByTagName("ul")[0].style.visibility="hidden"
    }
    }
  }
}

if (window.addEventListener)
window.addEventListener("load", buildsubmenus_horizontal, false)
else if (window.attachEvent)
window.attachEvent("onload", buildsubmenus_horizontal)

</script>

<div class="suckertreemenu">
<ul id="treemenu1">
	<li><a href="#" style="border-left: 1px solid black">Item 1</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>

			  <li><a href="#">Sub Item 1.3</a></li>
			  <li><a href="#">Sub Item 1.4</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>
<br style="clear: left;" />
</div>

<p id="iepara">Rest of content here></p>