how to register 2 letter domain?
You've got more chance of finding a blonde virgin than finding a two worded domain ;-)
unless you're talking about country codes, in which case you need to register your domain with a country code (there are probably some limitations.. like.. you have to find a server in that country to host your data)
Like, in your example, co.nz would be new zeland
(assuming their links are persisten)
Otherwise, check out godaddy for more info.
Due to the popularity of owning a domain, its becoming impossible to find a domain for your uses... so its rare to find anything 2 lettered...
I would assume that vizz is asking about regiserting in one of these domains, not how to register a two letter domain...
I learned something new, that co.cc is a free domain holder... I guess I didn't understand the question.