[dev] what shall I do if i want to know how OpenOffice handles MS office file format?

[hyz]

 Hello ,everybody!
    This is the first time I come here.I want to join the development of 
OpenOffice and I am very interested in how OpenOffice handles MS office file 
format.I have download the source code of openoffice,but I don't know how to 
start.What should I do?I am not familiar with this OpenOffice now .Will you 
please give me some suggestions?