As I understand html5shiv.js file "teaches" browsers like IE to process CSS3 properly:
<!--[if lt IE 9]>
<script src="scripts/html5shiv.js"></script>
<![endif]-->
Where should I include it - before styles tag or at the bottom of the page?
<!DOCTYPE html>
<html>
<head>
<title></title>
<meta charset="utf-8" />
<!-- Where to put this link to html5shiv? -->
<!--[if lt IE 9]><script src="scripts/html5shiv.js"></script><![endif]-->
<link rel="stylesheet" href="some.css"/>
</head>
<body>
<!--html content -->
<!-- scripts should be loaded after DOM is constructed -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script type="text/javascript">
// some scripts here..
</script>
</body>
</html>
If you get started with a new tool or code snippet or library and you don't understand it at a first glance, you really should start reading the manual!
See: https://github.com/afarkas/html5shiv