Beginner's Big Question... Inside codeigniter

[eluser]mlakhara[/eluser]
Hello everyone
I am new with codeigniter and I am trying to figure it out
in order to create a social network for my college.
I have been reading a lot of the documentation for CI which is
quite awesome, however I was wondering if there is any other
document that gives a sneak peek into the interiors of CI --
and explains that how the internals work like where is the CI sessions
stored, how does the loader class works etc.
All in all I am searching for something that removes the layer of abstraction
between implementaton and understanding.