Installing a new design from test domain

I have been asked to redesign a wordpress site for a client, I assumed the client had there own webhost where they were hosting WordPress as they have there own domain name. It turns out that actually the site is a wordpress.com site and a domain upgrade that has been purchased from the ′store′ menu.

So my question is how can I now transfer the installation I have on my test domain over to the clients domain. The easiest way would be FTP but I can′t find any ftp details and assume they dont exist.

There may be an obvious solution but I normally only work with www.remarpro.com setups.

Has anyone else come across this issue?

Any help is much appreciated.