The following code shows how to style fieldset.
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.0.4/css/bootstrap.min.css">
<style type='text/css'>
.fieldset {<!-- ww w .j a v a2s .co m-->
border: 1px solid #ccc;
padding: 10px;
}
</style>
</head>
<body>
<div class='container'>
<fieldset class="fieldset">
<legend>Main Section</legend>
<div class="row-fluid">
<div class="span6">some stuff here</div>
<div class="span6">
<fieldset class="fieldset">
<legend>A form inside</legend>
form here
</fieldset>
</div>
</fieldset>
</div>
</body>
</html>