Folding a napkin into a Christmas tree shape is an easy and festive way to add some holiday cheer to your table setting. To get started, take a square napkin and lay it out flat. Then, fold the napkin in half, creating a rectangle shape. Next, fold the bottom edge of the napkin up to the top edge, creating a triangle. Now, you'll need to make a series of small folds. First, fold the bottom left corner up to the top edge, creating a new triangle.