Next post this image in the gallery. It would be a great learning lesson for all. In a nutshell you have to think everything as simple form.
The desk is a box, the head is a oval, the body is an oval too. Then add light to the form.
In this case I would have light coming from up above.
Yes the photo has flat light so there is no obvious line that separates. You will have to use a bit of artistic license.
Thanks for the kind words.