on the confirm page, the where did you hear about us fied needs to capture the value posted from the checkout page:
<input type="hidden" name="Where_Did_You_Hear_About_Us" id="Where_Did_You_Hear_About_Us" value="<?php echo((isset($_POST["Where_Did_You_Hear_About_Us"]))?$_POST["Where_Did_You_Hear_About_Us"]:"") ?>"/>
Dreamweaver sometimes needs a nudge to see new database columns, see this post for details:
showpost.php?p=78376&postcount=2