1. Cut a shape of a Christmas tree on the front side of the card.
2. Tape stripes of green washi tape on the card insert. It does not matter at this point if the strips go over the edge of the insert. It will all be cut away in the next step.
3. Then cut along the sides of the insert to get rid of the excess tape.
4. Open the card and place glue all along the edges and around the tree. Then place the prepared insert behind the card front so that the colors face up and press the card closed. When the card gets opened again, the backside of this insert will only be seen.