What do I need to learn so I can make my own el. devices from simple circuits to RC cars?

PS: I know very little about electricity, circuits… Where can I learn everything from scratch?

I you can give me anything for free, like e-book or web site, it would be great!

Two parts to this, the theoretical knowledge and the practical skills. I would start by buying some electronic kits of whatever kind takes your fancy and learning to solder them together. By then you will begin to understand what you need to know, and can explore the internet more thoughtfully.
The starting point, as always, is learning how to do your own internet searches, where you will even discover the secrets of soldering if you look.