Dear Ahmad Zaklouta,
IMHO, first, you should understand the features of the board is satisfied with your purpose or not.
Second, you should be familiar with Linux OS. (ebook: The linux command line, Building Embedded Linux Systems By Karim Yaghmour).
The last, you could use the help-desk website such as www.beagleboard.org/chat or any forum relates to the Linux os or embedded Linux.
Hope it help. Good luck.
There is a book coming [1]. However I agree with the sentiments above, you're going to be struggling if you require very detailed information about the whole system.
For my final project, even though I had some base Linux knowledge I chose to use the Lego Mindstorm platform and I used the nxtOSEK operating system which is much simpler and easier to manipulate, however it doesn't have the wealth of software libraries Linux does, maybe worth a look....
[1] http://www.amazon.com/gp/product/1449345379/ref=oh_details_o00_s00_i00
Best Regards and Good Luck!
Jack.