This document is for people who want to write kernel modules. Although I will touch on how things are done in the kernel in several places, that is not my purpose. There are enough good sources which do a better job than I could have done.
The kernel is a great piece of programming, and I believe that programmers should read at least some kernel source files and understand them. Having said that, I also believe in the value of playing with the system first and asking questions later. When I learn a new programming language, I don't start with reading the library code, but by writing a small `hello, world' program. I don't see why playing with the kernel should be any different.