I found this cake pan at Walmart.  Its a Wilton pan, however the area where you see the appearance of ornaments on the cake are actually holes that go all the way through the cake after the cake is baked.  So after baking the cake, which I just used 1 box of white cake mix and made a simple butter cream icing, I started by taking most of the icing and tinted it green. I then used one of my star tips and did the whole tree with the star tip in green.

I left the empty area of the cakes where the holes were empty and then since I was not sure what to fill it with, I ended up then coloring the remaining icing red (it kinda turned out more pink then red) and filled in the holes with the red icing using one of my round tips. The only thing I would change in the future is I would probably fill it with something other than ALL icing since when you bit into that area all you get is icing. It would be good with a fruit filling or something. Other than that it tasted good and was festive for the holiday.  Enjoy!