サンプル
<!DOCTYPE html>
<html lang="jp">
<head>
<meta charset="utf-8">
<title>Bootstrap 101 Template</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<!-- Bootstrap -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" integrity="sha512-dTfge/zgoMYpP7QbHy4gWMEGsbsdZeCXz7irItjcC3sPUFtf0kuFbDz/ixG7ArTxmDjLXDmezHubeNikyKGVyQ==" crossorigin="anonymous">
</head>
<body>
<div class="container">
<a data-toggle="modal" href="#demoModal" class="btn btn-primary">Click Me!</a>
<div class="modal fade" id="demoModal">
<div class="modal-dialog">
<div class="modal-content">
<!-- モーダル・ヘッダー -->
<div class="modal-header">
<button class="close" data-dismiss="modal">×</button>
<h3 class="modal-title">Title</h3>
</div>
<!-- モーダル・ボディ -->
<div class="modal-body">
Hello World!
</div>
<!-- モーダル・フッター -->
<div class="modal-footer">
<button class="btn btn-primary">OK</button>
</div>
</div>
</div>
</div>
</div>
<script src="http://code.jquery.com/jquery.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js" integrity="sha512-K1qjQ+NcF2TYO/eI3M6v8EiNYZfA95pQumfvcVrTHtwQVDG+aHRqLi/ETn2uB+1JqwYqVG3LIvdm9lj6imS/pQ==" crossorigin="anonymous"></script>
</body>
</html>