Question

How do I do this?

Answer 1

Draw the lines as in the image.
Triangle AFC is a 30-60-90 triangle, so FC=6√3.
(Youcould also calculate this with the Pythagorean Theorem)
It is a well-know fact that CG:GF=2:1, So you know these two lengths as well.

If you look well at what you know now, you have the answer to both of the questions!