Trigger Order Status

[keweli]

I really want the status of an order to be change automatically.

E.g. when someone successfully pays through PayPal the order status changes to 'Payment Accepted'.
I know this is done in validation.php of the paypal module.

I have created a new status and want the status to change to it if a specific courier was selected.

I am sure with an if statement this can be done.

E.g. if ( courier is express)
{
$paypal->validateOrder($_POST['custom'], _PS_OS_PAYMENT_EXPRESS, floatval($_POST['mc_gross']), $paypal->displayName, $paypal->getL('transaction').$_POST['txn_id']);
}
else
{
$paypal->validateOrder($_POST['custom'], _PS_OS_PAYMENT_, floatval($_POST['mc_gross']), $paypal->displayName, $paypal->getL('transaction').$_POST['txn_id']);
}

thanks

[keweli]

I have figured out everything else, I just need to know how to generate the courier name/id needed to be compared in the If statement inside validation.php!

Please help!!!