Find the sun
The red ellipse is a representation of the elliptical orbit of earth where the dashed line is the major radius. Use the construction tools given to find the location of the sun (one foci of the ellipse).
It might be easier to hide some constructions if not needed to see so the construct is not too cluttered.
Remember the compass tool (sixth tools from the left) work by clicking 2 points for a radius and then where you want the center.