Moving from .com to .org

I have been reading a lot of forums on here about moving my site from .com to .org but I am still somewhat confused.. I am helping a friend create a website and he got .com thinking it had all the freedom of .org. There is nothing on his wordpress.com site that needs to be transferred since we haven’t “published” it yet, but how exactly do I get the domain to transfer. I know I need to change hosts, but is that all that I do? For example, when I get on bluehost.com it asks if I already have a domain or if I need a new one, do I just put that I already have one and put it in there? I’m sorry that this may sound redundant to all of the other posts, but I’m just having a difficult time understanding the directions since they’re all mainly targeted towards people who need to move their content as well. The important thing to us is he has to have the domain that he has already purchased through wordpress.com.

Thank you.