I was using my dad's shop and MIG welder, so he was able to give me an intro. A buddy of mine is a millwright and came over and kindly taught me some tricks which brought me welds up to an acceptable quality.

After learning, I'd have to agree with one of the other responses, learning by Youtube is probably feasible. It's safer than I expected (less concern about touching metal in the ground path) though I'd strongly recommend investing in quality gloves, a quality helmet, and good thick pants, and a long-sleeved shirt / overcoat.

I thought about taking a course but I found this way of learning a lot more fun and engaging (if you're fortunate, as I am, to have experienced people in your life).