jhcmc,
Please note that this is the Licenses, Activations and Customer Care forum, and should not be used for technical questions on the software. In the future, please post in the PrintShop Mail Design forum, which is for technical questions on the software and things related to it.
Now, to answer your question, as of PrintShop Mail version 7, we no longer prodive barcode fonts with it. Instead, it has a new barcode object that allows you to create barcodes. You can access it from the toolbar to the left in the PSM application, by clicking on the little barcode icon. Then, click on the new barcode, go to Windows->Properties, and you will be able to select the type of barcode that you want to use. You'll want "USPS PostNet" for the PostNet barcode. You can then edit the "ZIP" property to enter your zip code.
Hope that helps!
Regards,
Raphaël Lalonde Lefebvre