The source code for a game is in many hundreds or even thousands of source code files. The code is compiled into an .exe that is distributed to the user. Most game developers won't just give you the source code, because then you could copy it and turn it into your own game and sell it.
If you are serious about looking at game source code, you should browse a list of "open source" games:http://en.wikipedia.org/wiki/List_of_op ... ideo_games
The open source community consists of people who believe in sharing source code and giving software away for free - software like Firefox, BitTorrent, Linux, and the software that powers this forum are open source.
You can probably get started by studying the source code in some open source games, following some online tutorials, and getting a student copy of Visual Studio Express.