> Ultimately, my real interest in programming is to be able to create and understand networks of different kinds ...
> if there are grounds to cover first, please tell me.
Start by understanding the network protocols. That is the first step.
This classic is a stand-out choice:
TCP/IP Illustrated, Vol. 1: The Protocols by Richard Stevens
http://www.amazon.com/dp/0201633469/
There is no better place to start. You can start today, if you want.
EDIT: Hadn't noticed this when I made the post:
> After two weeks, I've finally finished my first book, Accelerated C++ for my first language.
Two weeks, from the time you started reading your first book?
You haven't finished your first book. You are nowhere near having finished it.
Go through the book once again; this time, attempt to do the exercises at the end of each chapter.
If you can do all (or almost all) of them, you have completed (or almost completed) the book.