https://www.codecademy.com/courses/make-a-website/lessons/bootstrap/exercises/connect-bootstrap?action=lesson_resume&link_content_target=interstitial_lesson
Did you create a link element with an href set to the Bootstrap URL?
<!DOCTYPE html>
<html>
<head>
<title>Skillfair</title>
<meta charset="utf-8"/>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap/.min.css"/>
integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7"
crossorigin="anonymous"
<link href='https://fonts.googleapis.com/css?family=Roboto:300,400,700' rel='stylesheet' type='text/css'>
<link rel="stylesheet" type="text/css" href="main.css">
</head>
<body>
<header class="container">
<div class="row">
<h1 class="col-sm-8">Skillfair</h1>
<nav class="col-sm-4">
<p>newest</p>
<p>catalogue</p>
<p>contact</p>
</nav>
</div>
</header>
<section class="jumbotron">
<div class="container">
<div class="row text-center">
<h2>Homemade Goods</h2>
<h3>This Year's Best</h3>
<a class="btn btn-primary" href="#">See all</a>
</div>
</div>
</section>
<section class="container">
<div class="row">
<div class="col-sm-6">
<p>kitchen</p>
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/kitchen.jpg">
</div>
<div class="col-sm-6">
<p>woodwork</p>
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/woodwork.jpg">
</div>
<div class="col-sm-6">
<p>gifts</p>
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/gifts.jpg">
</div>
<div class="col-sm-6">
<p>antiques</p>
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/antique.jpg">
</div>
</div>
<div class="row text-center">
<a class="btn btn-secondary" href="#">View Complete Catalogue</a>
</div>
</section>
<footer class="container">
<div class="row">
<p class="col-sm-4">© 2016 Skillfair</p>
<ul class="col-sm-8">
<li class="col-sm-1">
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/twitter.svg">
</li>
<li class="col-sm-1">
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/facebook.svg">
</li>
<li class="col-sm-1">
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/instagram.svg">
</li>
<li class="col-sm-1">
<img src="https://s3.amazonaws.com/codecademy-content/projects/make-a-website/lesson-4/medium.svg">
</li>
</ul>
</div>
</footer>
</body>
</html>
