Tutorial are not professional at all (by kids...)
Read Network Programming books (easy to find in ebook format)
A tutorial is a great way to learn the basics of subject in a relative small amount of time. When you understand the basics, you can always buy a good book to get you deeper in the theory.
I know you're probably not going to respond, but I'm just curious: Why do you keep posting these utterly useless replies? You're not helping anyone with comments like:
-- Read an ebook!
-- Use win32!
-- It's on MSDN