Here's another version of this technique that I used to make this card:
IC34, SC82 Pansies Under Glass by labullard at Splitcoaststampers
The easiest way I've found is using a very hot dry iron to bond the patterned tissue paper, stamped tissue paper or decorative napkins (only the top one-ply layer) to the shiny side of freezer paper.
Put a sheet of copy paper on your ironing board, then the freezer paper (I cut it slightly smaller than the size of my napkin image) shiny side up, then the decorative napkin/tissue paper (pattern side up), then another sheet of copy paper to protect your iron from the waxy stuff from the freezer paper. Then iron this "sandwich" for about 15 seconds.
You can crumple the tissue first for a more textured effect. For a smoother look you can iron the napkin first before the freezer paper step.
The edges can be prone to coming up if the bond isn�t perfect, which is why I layered acetate on top for protection.
If you use large sheets of decorative tissue paper, you can make wonderful envelopes out of it using any envy template.
Have fun!
Linda