In need of help, somehow I can't get over this one. Please help!

I've send some photos and file for your review here. It says Rebuild Errors: Sketches used for revolve features should contain a single, non-self-intersecting contour and either a single centerline or one that is currently selected.

I'd like to extrude on the surface with some contours. I was thinking of drafting a simple block which I can either rotate at a small angle of 5' - 15' to shape the bulky bridges between the two arcs. I'm stuck even after using several methods to have these bridges on the contour of the surface.

Can anyone share me how to get through this challenge?

Thanks everyone,
-az