Please don’t take this the wrong way, dude, but I seriously cannot tell if English just isn’t your first language or if you are typing terribly on purpose. Without any kind of clarification or answers to my questions, it’s going to be real hard to help you.
If you have a “social site” already, then I would guess it already uses PHP, in which case… continue to use that.
If what you are developing is an application, then have a look at java sockets. There are some good tutorials out there that will guide you through establishing a connection with a server and setting up communication.