you have to add the ser ice select list to the page first, go to the bindings panel and select WA eCart -> Shipping -> UPS Service.
the select list will need to be added to the checkout page.
for every form element that you add to the checkout page, you will need to add 2 things to the confirm page:
1) the confimr page has a collection of hidden form elements to capture the values posted from the checkout page, you need to add a new hidden form element with the same name as the one from the checkout page:
<input name="OrderPromotionalCode" type="hidden" id="OrderPromotionalCode" value="<?php echo((isset($_POST["OrderPromotionalCode"]))?$_POST["OrderPromotionalCode"]:"") ?>" />
2) Each form element has a corespondin set session value behavior on the confirm page.
on the sever behaviors panel, click the plus button and select eCart -> General -> Set Session Value.
Set the trigger to any form post.
set the name to the same as the form element.
click the lightning bolt next to value and select the corresponding form element from the form collection.
in the ups shipping behavior, bind the service to the session variable.