Hang in there. I have some pics on my website of some of my first attempts at trying to replace the lower inside door panel. There is no support across the entire door, so WOW.. are you ever screwed if you are learning welding and doing THAT! I cut that piece out three times, which of course warped the living crap out of EVERYTHING. I was very close to just finding another door. I did some research, YouTube videos, weldingweb forums, asked a lot of questions and yes, it IS technique. Now I butt weld everything and between welding magnets and butt weld clamps, and an understanding of proper technique all is good.
You are doing fine. Don't give up. Persistence is the order of the day!
