I hope that you have a Linux distribution on your system.
Assuming that you may try these books:
* Understanding the Linux Kernel - O'Reilly
* Linux Kernel Development - Robert Love , Novell Press
For more general discussions you may refer to:
* Operating System Principles - Galvin , Wiley Press
Minix is a Unix like Os , so you may consider starting with that. A very good reason to do so is:
* Operating system design and implementation - A. S. Tanenbaum
This book discusses the full source code of Minix Kernel.
My advice would be first get hands on with a linux machine, i mean learn the commands , shell etc and
then do some system programming(again there are some very boooks on that), and assembly language programming.
Then go for the kernel. I think you will be more comfortable that way.
The site for you is: http://kernelnewbies.org/
Note: Be sure to buy the book(edition) we discusses the kernel version of your interest.