Torque of a man doing exercises against a wall?

[imatreyu]

Homework Statement

The person in figure 8.31 weighs 800 N. the forces F1 and F2 have magnitudes of 100 N and 900 N respective. Assume the force of gravity acts downward through point A as shown. Determine the net torque on the person about axes through points A, B, and C perpendicular to the plane of the paper.

Please neglect the force values given in this picture
The angles are correct, however.
Picture: http://img153.imageshack.us/img153/3927/picture4cb.png

Homework Equations

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The Attempt at a Solution

I don't know where to start!
I don't know where to place the axis of rotation. And what about the lever arm?
I really don't know how to align my axis.

 

[imatreyu]

Here are the answers:
207 Nm clockwise
145 Nm clockwise
95.7 Nm clockwise