BuddyPress.org

I am new to bp, and I am looking to make a few changes to it. Before I even start changing anything I need to know what
some functions are and were are they located (searched but got blank page). Example I opened up header.php and seen a lot of
bloginfo () functions, now the system is pretty big so it can take me some time before I find were this function has been defined. Yet
I dont want to touch it unless I know what it is (even though it is self explanatory but still). Is there any doc that can show me where these functions in general are located? or what they mean in a more robust way? Another reason for this is, what if I decide to create a plug in for the system? If so I rather create it correctly than beat around the bush .

P.S: Great system
Thanx.