This is too broad of a question but...
Car Talk although I only listen to it once and a while for entertainment.
Overview - Wheeler Dealers on DiscoveryUK.com is a great show that goes into repair and repair tips.
Welcome to Goss' Garage! | Goss' Garage also has good tips, usually on a show called Motorweek.
These are some entertaining garage shows that can give some tips on repair that can be really helpful.
If you want to get your hands dirty, try something simple like changing a tire or oil. You'd need to have the appropriate tools and safety equipment though...
Techs at car dealers, have a big advantage over the home mechanic, like lifts, air tools, all the right tools, and for the most part step by step instructions on how to do things. If you follow directions well, you can become a tech assistant, no problem.
Also, poke around your car, or a friend's car and see if you can point out each component of an automobile and label them...Maybe even go to local car shows to look at old muscle cars and see how simple cars used to be.
The big thing is diagnosing problems. It is an art, and what takes the most experience, and what separates good mechanics from lousy ones... Is it a noisy wheel bearing, or a broken boot? A cupped tire or a bad shock, or both? The engine hesitates...is it bad gas? Is the head gasket blown???
When broken down (no pun intended) cars can be really simple.