freeradius implementation

Hi..

I am new to freeradius. I have downloaded freeradius-1.1.6. When i tried to run, it worked properly.
Now i want to understand the code flow(ie., the implementation) of the freeradius. But i dont know where to start and how to start.I want to know how authentication, authorization and accouting activities are implemeted.
What are the files i have to go thro? Please give some idea...
If u know any guide or book about the implementaion of freeradius, please tell me.



Thanks in advance...