Many of you requested that I have a tutorial on how to make the Secret Panel card. Thank you for asking and here is Part I, which will take you through the basic construction of the card's hidden panel. Have fun! :<)
Starting with a 5 1/2" x 8 1/2" piece of CS, fold it first in half and then each side in half again. This will form a 'tent' when you lay the card face down.
I pushed the center section back for this photo so you could see the three sections more clearly.
When the strips are in place, fold the card together.