New to Java

I have been given a assignment which I have to write a detailed description of the main method from the Server class (available from http://www.csee.umbc.edu/~pmundur/courses/CMSC691C/lab5-kurose-ross.html)

An example of the level of description that is required is
The parse_server_response method of the Client class: The method starts by initialising a local variable
to zero. In lines 342 to 362, the Client tries to read the three lines of the server response. If this is
unsuccessful for any reason, the catch clause (lines 366 – 369) is executed.

I am new to JAVA, so wondered what is the best way to go about it e.g. suggested tutorial on RTSP:Listening port etc and any websites which will help me in getting an understanding of this kind of coding.

It is quite frustrating as we were only taught the basic of OO principles and the assignment is asking us to explain the code.

Thanks