You need to know how to paper piece (foundation piece)
This free PP pattern is a part of Forest QAL, organised by me (Shape Moth) and Julianna @ Sewing Under Rainbow.
Tutorial for the pattern:
You can find all the details about Forest QAL here: http://shape-moth.blogspot.de/2013/03/forest-qal-comming-soon.html
The pattern is for personal use only. (c)2013 Shape Moth. The pattern content within the pdf is copyrighted and cannot be reproduced electronically or copied and distributed. This pattern is a Shape Moth design.