Creating a web browser from scratch is an amazing feat, its hardly ever done by one programmer and a simple tutorial wouldn't cut it.
but if you really want to, a good place to start would be learning to parse HTML. this could be done several ways, but the problem is finding a fast way to do it. regular expressions just wouldn't cut it. plus this entails that you have a complete and in depth knowledge of HTML in the first place.
I guess if you were really serious about it you have 2 ways to get started. you can get the source for the actual webcontrol from .net and read up, or you could download the source for firefox and start transalting it into C#.