<b>Add finishing touches</b>
To add text to the inside of the card, grab the text tool and draw a text box over the photo, matching its dimensions; then type some text. You may have trouble seeing what you've typed, because it will appear superimposed on the photo. Nevertheless, the contents of this text box will ultimately go on the inside right panel of the card. To make that happen properly, though, we need to render the card's cover temporarily invisible. No problem: Photoshop Elements has treated the text as a new layer of the card's art.
In the Layer palette on the right side of the screen, make the Background layer (the one containing the cover photo) invisible by clicking the eye-shaped visibility icon. Now you can see the inside of the card--and the text box--much more clearly. Enter the message. When you're done, you'll have something that looks similar to the image shown here, with text and images overlapping each other in an illegible mess.
Now you just have to print the card properly. Make the Background layer visible; make the text layer invisible; and click Print. Then load the paper back in the printer; make the outside of the card invisible and the text visible; and click Print again. You may have to experiment with the orientation of the paper to perform the second pass properly. For help, check your printer's paper tray for a symbol indicating which side of the paper gets printed on.
You're all set now except for envelopes and stamps...but wait! What if you don't want to go the snail-mail route? It's easy to share your holiday snaps online.