If you use all the exact code you should get what you want. Make a backup of style.css first!
Edit style.css
Background - Change bp.gif to new image
body {
background:url("images/bp.gif") no-repeat scroll center top #F3F2E8;
color:#35383D;
font-family:"Trebuchet MS",Arial,Helvetica,sans-serif;
font-size:12px;
margin:0;
padding:0;
}
Header Height - Add height 350px
.Header {
height:350px;
margin:0 auto;
width:1005px;
}
Menu Bar - Edit top to move down - the 4th number in Padding to move right. I dont know where you want it.
.Menu {
float:left;
padding:0 0 0 90px;
position:absolute;
top:350px;
width:470px;
}
Id also make this change to push the content down some depending on where you want the menu bar.
.CON {
background:none repeat scroll 0 0 #FFFFFF;
border:1px solid #E1DFD0;
float:left;
padding:50px 15px 5px 25px;
width:965px;
}