This technique card is made really easy because of the waterfall thin cut die that Close to My Heart came out with in September. The elements of this die (Z3777) are shown below. All the pieces you need to finish this card are included in this die set - found on my CTMH website.
Here are a few other photos showing how it looks as you pull it open.
The snowflakes are embossed with white on the Blue Belle color of the year cardstock. The sentiment is stamped in Sapphire.
The snowflakes are from the Elegant Snowflakes stamp set that comes with coordinating thin cut dies (Z3899)
This card is really easy to put together, and is a part of my December card kit. Contact me if interested