*{margin:0;padding: 0;list-style: none;}
#main{
width: 1000px;
margin:0 auto;
}
#head{
background:url(#.../images/head.png);
display:block;
float: left;
width: 1000px;
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<link rel="stylesheet" type="text/css" href="css/001.css">
</head>
<body>
<div id="main">
<div id="head">
<div class="nav">
<a href="#">1</a>
<a href="#">1</a>
<a href="#">1</a>
<a href="#">1</a>
</div>
</div>
<div id="content">
</div>
</div>
</body>
</html>
