How do I put my Delta Boarding pass on the passbook app?

did youo check in online? did they emailed your boarding pass? Did you use the Delta iOS app? If so, look for a link saying "ADD" and tap that. It will take your boarding pass to the passbook app.

Once you check in to your flight online, either by using a browser like Safari, or the Delta app on your iPhone or iPad, the boarding pass will be available in the Delta app. You can then share the boarding pass to the Passbook app.

If you do not have the Delta app on your phone you can download it from the App Store.