I'm no expert - but if you can make a tiny game (like you did via your 3d pong) and can jump into learn about UDP and TCPIP (Two common "specifications" for communication over a IP based lan (like the internet) and how to get WinSock (Windows DLL / API) or some other tool (that sits on top of winsock) or even try your hand in Linux (sockets library) and can get a chat server/client going - just to type messages from one machine to another - You're well on your way.
I know we are mostly C++/C# here - but I code in FreePascal ALOt and I have this guy's home made web server - its not multithreaded like mine or anything but its REAL REAL small.. the whole thing in under a 1000 lines!!! (Which isn't much) It is mostly comments - a russian kid did it but the networking part is only a few lines - the rest is http stuff mostly whech is just text riding on the TCP/IP protocol.
Its called nYume .. yup - didn't misspell -
nYume you might find it online - if not I have it so ask. P.S. FReePacal is SO easy to read compared to C++ - it reads like BASIC but is as fast C++.