I don't know how to make it automatically cycle through, but you can let the winner know that they won by putting this with the part of the script that picks the winner:
PHP Code:
$pm = new PrivateMessage(); // Send the winner a pm
$pm->setsender('AdminUsernameHere');
$pm->setrecipient($winner);
$pm->setmessage("You won the raffle! Congratulations! {$pool} CURRENCY has been added to your account.");
$pm->post();