Are you asking about video transitions like turning the pages of a photo book? Where are you seeing the 'flat' greeting cards?
[EDIT] Photoshop Elements has greeting card features including Folded. If that is what you are looking for you will get better advice from the Photoshop Elements forum.
Insanity is hereditary, you get it from your children
Message was edited to add PSE details.
In the Elements Organizer, there are a number of greeting card designs, both folded and flat.
You can also find even more if you follow the links from this Organizer workspace to online services like KodakGallery.