Rekha is still right!
When you call your script like this :
http:\www.xxxx.com\confirm_acount.php?id_confirm=a1b1c2d4
.. you will automatically have access to the variables from the querystring. That means that if you do this in your script :
<?php
echo "Random : " . $id_confirm;
?>
.. you will see :
Random : a1b1c2d4
Easy isn't it?
If you need further help, please do not hesitate to write me an email. =8-)