Using sheet metal in fusion 360

I am struggling with sheet metal in fusion 360 . I am drawing a simple design for an oil tank.
It is simple enough to draw a wireframe in sketch but turning it into a solid is just frustrating. The flange tool is difficult as the tank does not have straight right angle edges.

I am insure how to upload my progress so far as it seems in fusion all the drawings I do are kept in the clouf