This forum limit only 4 images per post - so I have to split my answer into several replies.
5) You now have a half-circle
6) 3) Cover the right half + "some more" with a square. Use the guide-lines for some eye-measure. You do
NOT want to put the left of the sqaure directly on the middle of the half circle.
7) Subtract the selected shapes again using the
Edit -> Shapes -> Subtract Shapes menu
8) You now have the first quarter of the outer circle in place
