The following code shows how to create Nested rows.
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css">
<style type='text/css'>
[class*="span"] {
border: 1px solid black;
}<!--from ww w. j a v a 2 s . c o m-->
.row-fluid [class*="span"] {
margin-left: 0;
}
</style>
</head>
<body style='margin:30px'>
<div class="row">
<div class="span5">span5</div>
<div class="span3">span3</div>
<div class="span2">
<div class="row-fluid">
<div class="span12">span2</div>
<div class="span12">span2</div>
</div>
</div>
<div class="span2">span2</div>
</div>
<div class="row">
<div class="span6">
<div class="row-fluid">
<div class="span12">span6</div>
<div class="span12">span6</div>
</div>
</div>
<div class="span6">span6</div>
</div>
</body>
</html>