Apps don't show up in Passbook book, passes do. The apps in the featured Apps for Passbook room all have some way to add passes to Passbook, but the apps themselves don't show up in Passbook. Try visiting coupons.com on your iPhone to add some quick passes to Passbook.
Also, did you read the support page on Passbook? That might help. http://support.apple.com/kb/HT5483