{source}
<!-- You can place html anywhere within the source tags -->
<script language="javascript" type="text/javascript">
// You can place JavaScript like this
<iframe width="853" height="480" src="https://www.youtube.com/embed/o0OHBgKRobE" frameborder="0" allowfullscreen></iframe>
</script>
<?php
// You can place PHP like this
?>
{/source}