.bg-primary,.bg-success,.bg-warning,.bg-danger,.bg-info classes are used to give different colours to the backgorunds.
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Bootstrap css helpers Example</title>
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Background colour</h2>
<p class="bg-primary">Background is in primary style.</p>
<p class="bg-success">Background is in success style.</p>
<p class="bg-warning">Background is in warning style.</p>
<p class="bg-danger">Background is in danger style.</p>
<p class="bg-info">Background is in info style.</p>
</div>
</body>
</html>
