ahí dice... sólo tienes que leer el código y te indica lo que va en el head y en el body
...
<!-- TWO STEPS TO INSTALL FULL SCREEN2:
1. Copy the coding into the HEAD of your HTML document
2. Add the last code into the BODY of your HTML document -->
<!-- STEP ONE: Paste this code into the HEAD of your HTML document --><HEAD>
<SCRIPT LANGUAGE="javascript">
<!-- This script and many more are available free online at -->
<!-- The javascript Source!!
http://javascript.internet.com -->
<!-- Begin
if (this.name!='fullscreen'){
window.open(location.href,'fullscreen','fullscreen,scrollbars')
}
// End -->
</script>
</HEAD>
<!-- STEP TWO: Copy this code into the BODY of your HTML document --><BODY>
<a href="javascript:window.close(self)">Click here to return to normal window size</a>
<p><center>
<font face="arial, helvetica" size"-2">Free JavaScripts provided<br>
by <a href="
http://javascriptsource.com">The javascript Source</a></font>
</center><p>
<!-- Script Size: 0.83 KB -->
Un saludo. Nemrod.