If you're an autodidact you've done most of your learning on your own, outside of school. Having learned Greek and Latin, as well as landscape painting and auto repair, without any formal training makes you quite the autodidact.
Auto- means "self" and "didact" comes from the Greek word for "teach," so an autodidact is a person who's self-taught. Being the autodidact that you are, instead of calling the plumber you bought some manuals and began to learn the trade yourself. You should learn scuba diving next, now that your apartment is underwater.