To do this tutorial you must have a great understanding of the pen tool in ADOBE PHOTOSHOP, i will not go throu each individual stage and walk you throu every little thing i do, you will be left to your own devices, but will help you the best i can.

Create a new layer and name it "shadows" then select your "pen tool" and select all the shadows then use fill path, fill it with the color black (to see where the shadows should be just hide your base color layer).