How to implement chat with central server?

I'm trying to program chat that has a central server (not LAN/WLAN).

I am also working on a c++ program that should connect to that server and interact with it to have a fluid chat.

My problem is that i have absolutely no experience with web programming, so I don't know which protocol I should use.

The chat server should also work when using TOR to send data.

I thought about using Apache with PHP and MySQL-database on the server and then connecting to the website over TCP Sockets and HTTP but I don't know how to use HTTP-requests to tell the server to write something in the chat-database.

Probably this is not the best solution, so I would very thankful if someone could tell me a way to achieve my goal or give me some links to good Tutorials.

(The c++ program is not the problem, it is already able to send a HTTP request, receiving the answer and then printing it out.)