Welding is a great skill for a prop master or prop maker to have, though it can be a hard one to begin learning. The best way to learn is to have someone teach and guide you as you practice on your own. Whether that’s possible or not, it is also a good idea to watch some videos on welding to pick up background information and to get a different perspective on some of the techniques.
I discovered Kevin Caron’s videos on welding; he has dozens of videos covering all sorts of welding styles and techniques. His background is in metal art and fabrication, so the way he demonstrates welding is close to how a props artisan approaches welding. We rarely have to deal with all the technical information one might get with a traditional welding course, and it can be easy to get overwhelmed with all of that when you are just starting out and simply want to join a few pieces of steel together for a static prop.