The best way to learn about cars is to start fixing stuff yourself and learn! Buy a shop manual, and do a maintenance item. If something breaks, you have the shop manual and you can fix it!
The best part is, your car won't run again until you fix the problem, so it gives you incentive to learn
. I don't know half as much as many of the other guys on this forum, but what I've learned I have picked up from doing work on the car myself.
If you need a basic understanding of how engines work, check out www.howstuffworks.com!