I have completed a chat messenger with java socket programming. It's run on localhost, so clients can locate it. If i want to run the server side part of it on a web server, then what i should do? how could the client programs will find the ip and connect with server program?

You can give server ip to the client application instead of localhost

But the main problem is how can i run a server side socket program on a server hosting. i don't know the process. any kind of advice will be appreciated. :)

Create a jar for the server program and run in the server same as you runned in local machine.