You really have a lot of free time in your hand, haven't you? AFAIK, most browsers were written in C++, not all users have the .NET framework installed on their computers and if they do it might not be the version you need.
This could take you years but anyway, there are many open source browsers out there, FireFox, Google Chrome .. etc, you could start by having a look on the code, good luck with that :)
