try this...:)
.header
{
background-image:url('images/thCAUUWRRV.jpg');
height:100px;
}
.content1
{
float :left ;
height:400px;
width:600px;
text-align:center;
background-image:url('images/609094[1].jpg');
}
.content2
{
background-image:url('images/599999[1].jpg');
float:right;
height:400px;
width:600px;
}
and be sure with Image URL.