best way to repair this?

Go to Hobby Lobby or an art supply store and get some large water color paper to make templates of the panels you need to make. Cut them to size and transfer them on to the sheet metal. You can get the sheet metal from an auto body paint supply or through J.C. Whitney. If you are new to body work, read up on the subject or talk to some people who know what they are doing. Your car needs major surgery, but don't let that scare you off. You've got to start somewhere. You will have to cut ALL that rust out and weld or glue (yes I said glue) the panels in place. You will have to get some basic tools for body work and just by trial and error make it all work. Once you get a feel for what you are doing, your work will improve as you go. I'm really not a professional body man, but I have a few tools and do all my own fabrication work. I'm not the best, but I can do work that is satisfactory to my own needs. Roll up your sleeves (or roll them down if you're going to weld) and get at it with confidence!! The panels pictured here were not hard to make, you can do this!!
now there's an awesome reply. haha.