I have put together a very simple tutorial, which will work great for anyone who has done paper piecing before. If you are new to paper piecing, Faith from Fresh Lemons has a great tutorial here, which is for a different pattern, but has great pictures and really clear instructions which should get you started.
Here is a diagram showing the dimensions for the tree blocks. I just drew nine of the tree blocks out onto freezer paper, four in a row to speed things up. I then cut each tree block out so that I had nine individual units.
I then cut each tree block into two pieces along the dotted red line, so I was left with the triangle piece and the trunk piece.
Then, I paper pieced the tree blocks in the order shown below. A couple of tips. The first (and crucially important one) - I don't include seam allowances on my paper piecing templates (I find it easier that way) but make sure you leave a quarter inch seam allowance around the outside of each piece of the tree block. The second - make sure you reduce your stitch length, and backstitch at the end of each line - this will help a lot with removing the paper when you're done.
My preference is to leave the paper on the blocks until I have stitched them together, and sashed them out. This is because there are inevitably bias edges which can be stretched and warped if you have to pull on them before they're secured.
I hope this tutorial is useful - please feel free to let me know if you have any questions in the comments.
P.S. - don't miss out on my giveaway as part of Quilting Gallery's Blog Hop Party - all you need to do is leave a comment on my giveaway post.