It's really simple to do and looks so effective, I made 2 to stand either side of the mantlepiece.
Here's the link for how to fold the book. http://www.readersdigest.com.au/make-a-christmas-tree/
This link uses a Reader's Digest but I didn't have one so I used an old book. Bit of trial and error as to how much to use, in the end I used 1/3 of the book, about 150 pages. The star on top is made with cocktail sticks snapped in half and held together with beads on wire. The ribbon and beautiful birds were from Hobbycraft, the stars and heart buttons I already had.