how to create an application for client and server through any port available using Red Hat Linux.. give some link to refer...

perhaps you want to start with a programming language, not the actual operating system.

Yes, first you need to choose a web scripting language in which you wish to develop your application. If you are not familiar with this then you can hire a programmer to develop it for you. Later you will have to find a better host to host your web application.

you can just use netcat or socat why reinvent the wheel