Please see the following links for more information.
SELinux: NSA's Open Source Security Enhanced Linux - O'Reilly Book
An excellent and comprehensive book published by O'Reilly providing a detailed overview of SELinux. This book gives you just about everything you need to know to understand and configure Security Enhanced Linux.
Read more about this book.
The NSA run a mailing list for discussion of all things SE Linux. Follow the instructions at https://www.nsa.gov/selinux/list.html to subscribe. The same URL describes how to obtain list archives.
Getting Started with SE Linux HOWTO: the new SE Linux
My document on how to get started with installing and using SE Linux can be found here.