This is a sort of sad topic for me. I know that my mom intended to teach me to cook (there were specific dishes she made that had been passed down through the family that I know she intended to pass on to me) but unfortunately she died of cancer, somewhat unexpectedly, before she got the chance. I was very close to her and I really regret not having that time together.
So I learned to cook mostly though cookbooks and cooking magazines. I'm more into magazines than cookbooks. I do a lot of experimentation but I do sometimes make a recipe exactly the way it's called for. I'm not very good at making recipes up; I usually have to start with some instruction. I used to be into baking as well but now it's too hard to fit baked goods into my calorie restriction so I've mostly given it up (except for the Fiber One Muffins that I make every week).
My newest thing is canning and preserving. Because we have a garden and because I want to exercise portion control, canning and preserving is the perfect thing for me. We have a guava tree and every year I make guava jelly. Last year I made around 60 half-pints. Flavors included regular guava, guava cinnamon, raspberry guava, guava ginger, guava cinnamon ginger, and rasberry cinnamon guava. During the height of guava season, I have quite the production system going. Mostly we end up giving the jelly way (really, how much jelly can two people eat?) but it makes a great gift and most people request more. Over the past year, I've also canned green tomato salsa, green tomato sauce, dill bean pickles, lemon rosemary been pickles, and lemon rosemary asparagus pickles. If I get enough eggplant, I'll be making eggplant pickles this year. My mom was big into canning; she canned tomatoes every year and even though I don't have any of her recipes, it is still a nice connection to her.
And I've definitely made things that were inedible. There were the salisbury steaks that actually caught on fire

and a turkey chili that I put way way way too much chili powder in

(I didn't realize chipotle chili powder was so much stronger than regular chili powder). Also, a sauted fennel and chard over polenta dish that I accidently dumped half the salt shaker into

. In fact, the green tomato sauce didn't come out so well. The recipe annoyingly did not give any clue as to how much salt to add and I over-estimated, based on the quantity of salt required for the salsa, which came out fantastic. Since I was canning it and salt was the only preservative going into it, I didn't want to underestimate but erred too far in the opposite direction. And there have definitely been a couple batches of guava jelly that reached the jujubee stage (e.g., way too hard).