To enable embedded plupper window in your webpage add this line to your plupper code.
plupper.enableEmbedded("500px");
Function takes one parameter - width.
<html>
<head><title>TEST</title></head>
<body>
<script src="https://www.google.com/jsapi"></script>
<script type="text/javascript"
src="https://static.plupper.com/js/plupper.js"></script>
<script type="text/javascript">
plupper.init("accountName@plupper.com");
plupper.enableEmbedded("500px");
</script>
</body>
</html>