Buy a mini, let it break, take apart offending item, learn about it, fix it. 3 years ago i hadn't a clue about cars really, i knew basics but not what really goes on... as the mini broke down i picked stuff up, i can change a headgasket and wheelbearings at home, ball joints, cv joints, cv boots, radius arms, fuel pumps, carbs, rockers, rocker clearance. My gearbox has just gone, so now this gives me the opportunity to look at wtf is in that box that makes the car go vroom in the first place!
Fixed. My old tutor was very insistent on it. As for learning how cars work, it may depend on whether there are specific parts of a car you want to learn about or the whole thing. Also whether you want to know how something does what it does or why something does what it does. The only website suggestion I can make is Wikipedia.
I think the sad thing is, i can tell you more about how an airplane engine works (both prop and jet) rather than explain a car engine. Airplane engines are much easier to work on too.
