I Would like to have a service like uni.cc where they had a subdomain/domain like system where you you register a domain and have it pointing to dns name server is this possible but i am able to create my own extensions eg .com.org and ss.nz and stuff like that?

You can do this without much work in php.

$_SERVER['HTTP_HOST'] will return the domain that the user typed in. You can easily strip out the www. and parse it to get the subdomain.

Once you have the subdomain do a lookup in a table or a flat file for the matching name. Then forward the user to the domain.

You can not create your own top level extension. Icann has the power to do this.

How can i be a company like icaan?

http://en.wikipedia.org/wiki/Icann

So how can i become like Icann?

You don't. ICANN handles top level domains, and thats it.

what if i can is that possible?

No, not really.

services like uni.cc may "emulate" having their own tld, by using a subdomain solution, uni.cc is a top level domain, they alllow users a free sub domain, e.g user.uni.cc