The following code shows how to customize navbar.
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/bootstrap/3.0.0-rc1/css/bootstrap.min.css">
<style type='text/css'>
.navbar {<!-- w w w . ja v a 2 s . c om-->
width: 600px;
margin: 0 auto;
display: block;
background-color: black;
}
.nav {
text-align: center;
}
</style>
</head>
<body style='margin:30px'>
<div class="container">
<div class="navbar">
<ul class="nav navbar-nav">
<li class="active"><a href="#">Home</a></li>
<li><a href="#">Home</a></li>
<li><a href="#">Home</a></li>
<li><a href="#">Home</a></li>
<li><a href="#">Home</a></li>
</ul>
</div>
</div>
</body>
</html>