His simple, non-rotating AC welder was smaller, lighter and less expensive than the DC units currently available. Miller have a brilliant web site to help the welder fabricator. Full of Resources on all welding applications, Apps for weld calculations and Safety Precautions in the work place.
Welding is a skill that needs to be developed over time, with a piece of metal in front of you and with a welding gun/torch in your hands. There are many online tutorials, youtube videos and forums to help you develop into a MIG welder. MIG welding was developed in the 1940's and 60 years later the general principle is still very much the same.