Trouble creating dropdown menu in header

Any help would be appreciated… Please refer to the website: http://www.you-dude.com

I am creating a website for a friend and I am trying to implement a dropdown navigation menu into the header. I am currently unable to move the navigation bar where I would like. For some reason the header image is blocking my navigation bar, how can I fix this? Also, if I may ask for some help figuring out how to customize the code I got for this navigation bar, I would really appreciate it!

Here is the CSS style code I am using for the navigation bar (I put it in a box called “cssmenu_box” because I thought it might be easier to move around, but I am not sure I really need this either):

#cssmenu_box {
     margin:-10px 140px 30px 0px;
     float:right;
     z-index:10;
}

ul.cssMenu ul {
        display:none
}
ul.cssMenu li:hover>ul{display:block}
ul.cssMenu ul{position: absolute;left:-1px;top:98%;}
ul.cssMenu ul ul{position: absolute;left:98%;top:-2px;}

ul.cssMenu,ul.cssMenu ul {
	margin:0px 0px 0px 0px;
	list-style:none;
	padding:0px 1px 1px 0px;
	background-color:#A5A5A5;
	background-repeat:repeat;
	border-color:#A6A6A6;
	border-width:0px;
	border-style:solid;
        z-index:10;
}

ul.cssMenu table {border-collapse:collapse}ul.cssMenu {
	display:block;
	zoom:1;
	float: left;
}

ul.cssMenu ul{
	width:100%;
}

ul.cssMenu li{
	display:block;
	margin:1px 0px 0px 1px;
	font-size:0px;
}

ul.cssMenu a:active, ul.cssMenu a:focus {
outline-style:none;
}

ul.cssMenu a, ul.cssMenu li.dis a:hover, ul.cssMenu li.sep a:hover {
	display:block;
	vertical-align:middle;
	background-color:#FFFFFF;
	border-width:0px;
	border-color:#FCEEB0;
	border-style:solid;
	text-align:left;
	text-decoration:none;
	padding:5px;
	_padding-left:0;
	font:normal 11px Sans-serif;
	color: #000000;
	text-decoration:none;
	cursor:pointer;
}

ul.cssMenu span{
	overflow:hidden;
}

ul.cssMenu li {
	float:left;
}

ul.cssMenu ul li {
	float:none;
}

ul.cssMenu ul a {
	text-align:left;
	white-space:nowrap;
}

ul.cssMenu li.sep{
	text-align:left;
	padding:0px;
	line-height:0;
	height:100%;
}

ul.cssMenu li.sep span{
	float:none;	padding-right:0;
	width:3;
	height:100%;
	display:inline-block;
	background-color:#A6A6A6;	background-image:none;}

ul.cssMenu ul li.sep span{
	width:100%;
	height:3;
}

ul.cssMenu li:hover{
	position:relative;
}

ul.cssMenu li:hover>a{
	background-color:#FF1C1C;
	border-color:#4C99AB;
	border-style:solid;
	font:normal 11px Arial;
	color: #FFFFFF;
	text-decoration:none;
}

ul.cssMenu li a:hover{
	position:relative;
	background-color:#FF1C1C;
	border-color:#4C99AB;
	border-style:solid;
	font:normal 11px Arial;
	color: #FFFFFF;
	text-decoration:none;
}

ul.cssMenu li.dis a {
	color: #AAAAAA !important;
}

ul.cssMenu img {border: none;float:left;_float:none;margin-right:5px;width:16px;
height:16px;
}

ul.cssMenu ul img {width:16px;
height:16px;
}

ul.cssMenu img.over{display:none}
ul.cssMenu li.dis a:hover img.over{display:none !important}
ul.cssMenu li.dis a:hover img.def {display:inline !important}
ul.cssMenu li:hover > a img.def  {display:none}
ul.cssMenu li:hover > a img.over {display:inline}
ul.cssMenu a:hover img.over,ul.cssMenu a:hover ul img.def,ul.cssMenu a:hover a:hover img.over{display:inline}
ul.cssMenu a:hover img.def,ul.cssMenu a:hover ul img.over,ul.cssMenu a:hover a:hover img.def{display:none}
ul.cssMenu a:hover ul{display:block}

ul.cssMenu span{
	display:block;
	background-image:url(http://www.throughtheconcreterecords.com/youdude/wp-content/themes/datagrid/images/cssmenu/arrv_blue_2.gif);
	background-position:right center;
	background-repeat: no-repeat;
   padding-right:8px;}

ul.cssMenu li:hover>a>span{	background-image:url(http://www.throughtheconcreterecords.com/youdude/wp-content/themes/datagrid/images/cssmenu/arrv_white_2.gif);
}

ul.cssMenu a:hover span{	_background-image:url(http://www.throughtheconcreterecords.com/youdude/wp-content/themes/datagrid/images/cssmenu/arrv_white_2.gif)}
ul.cssMenu ul span,ul.cssMenu a:hover table span{background-image:url(http://www.throughtheconcreterecords.com/youdude/wp-content/themes/datagrid/images/cssmenu/arr_blue_2.gif)}
ul.cssMenu ul li:hover > a span{	background-image:url(http://www.throughtheconcreterecords.com/youdude/wp-content/themes/datagrid/images/cssmenu/arr_white_2.gif);}
ul.cssMenu table a:hover span{background-image:url(http://www.throughtheconcreterecords.com/youdude/wp-content/themes/datagrid/images/cssmenu/arr_white_2.gif)}
ul.cssMenu li a.cssMenui0{
font:n;
}

ul.cssMenu li a.cssMenui0:hover{
font:o;
}

Here is the code I am using in my header.php file:

<!------ CSS MENU ------>
<div id="cssmenu_box">
<ul class="cssMenu cssMenum">
	<li class=" cssMenui0"><a class="  cssMenui0" href="#">OEM Products</a></li>
	<li class=" cssMenui0"><a class="  cssMenui0" href="#"><span>End User Hardware</span><![if gt IE 6]></a><![endif]><!--[if lte IE 6]><table><tr><td><![endif]-->
	<ul class=" cssMenum">
		<li class=" cssMenui"><a class="  cssMenui" href="#">RTK Systems</a></li>
		<li class=" cssMenui"><a class="  cssMenui" href="#">Postprocessing</a></li>
	</ul>
	<!--[if lte IE 6]></td></tr></table></a><![endif]--></li>
	<li class=" cssMenui0"><a class="  cssMenui0" href="#"><span>End User Software</span><![if gt IE 6]></a><![endif]><!--[if lte IE 6]><table><tr><td><![endif]-->
	<ul class=" cssMenum">
		<li class=" cssMenui"><a class="  cssMenui" href="#">GeoID</a></li>
	</ul>
	<!--[if lte IE 6]></td></tr></table></a><![endif]--></li>
        <li class=" cssMenui0"><a class="  cssMenui0" href="#">Turn-key Systems</a></li>
</ul>
</div><!-- end css menu box -->

<!---------- end CSS MENU ------->

Please help! Thanks!