I have a HTML website template and I would like to add AdSense but I have to confess I am very into HTML coding, can you tell me where should I paste AdSense code

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Website Title</title>
</head>
<body>
You can add AdSense here anywhere you like!
</body>
</html>