how do i do this

suppose I come to know that ICANN is going to intridice a new extension called say .new . How can i register names before it becomes available for public registeration. how do they register domain names like sex.com , etc...

 

All of the premium names like that are not available for registration by anyone, as far as I know.

 

no you can then how else people sell those kind of domains

 

Well, it really depends. Some registrars may allow pre-order and some don't but there is no guarantee you get the names especially if they are popular.