Ajax auto update?

[EchoFool]

Hey i am trying to make a chat script with one page that auto loads a php function to list the logs which then creates the effect the page is "live" but without the appearance of it refreshing... i tried this:

 

shout.php

<script type="text/javascript"> <!--
new Ajax.PeriodicalUpdater( 'shout.php')
  {
    method: 'get',
    insertion: Insertion.Top,
    frequency: 1,
    decay: 0
  });
</script>

<?php
function read_entires($UserID,$Type){ 
//load logs and display them from query and while loop
}
read_entries($_SESSION['ShoutboxUsername'],'norm');
?>

 

But i fear its beyond my knowledge here and i got this on a tutorial site - what am i doing wrong ? :S