Javascript auto refresh code

I am not sure how to make this code auto refresh every 8 seconds, please can you point me in the right direction or show me a code.
CODE:

Code (text):

<?php

  $query = mysql_query("SELECT * FROM users WHERE username=’$user’ AND admin=’1′");

  $numrows = mysql_num_rows($query);

  ?>

  <li><a href=’chat.php’><span>Chat <?php if($numrows == "1"){echo "<b><font color=’red’>(!)</b></font>";} ?></span></a></li>

Thanks

See original post by shivampaw