Developers will have to include the gree.css and gree.js files that have been downloaded. jquery.js must also be included as a dependency. For example:
<!DOCTYPE html>
<html>
<head>
...
<link href="styles/gree.css" rel="stylesheet" />
</head>
<body>
...
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="scripts/gree.js"></script>
</body>
</html>
See the rest of the documentation here: https://greejs.herokuapp.com/documentation.html