This tree folding technique is easy to follow on splitcoaststampers site here. It works great with double sided paper like our Background and Texture Paper. Add a little Kraft cardstock for the tree trunks to ground them to the card. A zip strip or part of the striped B&T paper makes a nice "line" to stamp "JOY" from the Very Merry stamp set.
The sparkly stars at the tops of the folded trees are from the City Sidewalks Complements.