You could google how to do a simple fork server in c/c++ and after you have that working you just need to do something like this:

stringstream response; response << "HTTP/1.1 200 OK\r\n" << "Server: BTB Auction Updater 1.0\r\n" << "X-Powered-By:BTB Update Engine\r\n" << "Content-Length: " << msg.length() << "\r\n" << "Content-Type: text/html\r\n\r\n" << msg;

  int n = write(s, response.str().c_str(), response.str().length());
  if(n < 0) error("Error writing to socket");

to write back a valid header that a browser will understand