Post subject: php form help PLEASE!

I have form "A"

<?php echo $form->create(false, array('url' => "https://{$site['ssldomain']}/billing/".$site['domain'], 'id' => 'payment_form')); ?>

how to add css form id to it?

id="address_form"

You can't do it there.
It's done on whatever the page is being displayed .... the form page.

Unless I'm seeing it wrong.
Is that a function actually displays another file?