Obviously, without pictures, it's hard to tell you exactly what to do about the door. But this is something to consider. A used door from a southern or western salavge yard will probably run you no more than $150 to $250. While doing the work yourself is cool, just don't sink more into the door in time, tools and materials than the cost to replace the door.

The community college courses for doing body work is a good suggestion. I'm heading back in the fall for welding. Good luck with the project!