Moving a test Multisite to a different subdomain

http://www.clarendon.org is our main website, and I have to keep that running. I set up a multisite website called heartofarlington.info. I also have clarendonalliance.org (all of these are on Bluehost. I want to move and rename heartofarlington.info to clarendonalliance.org, get all the path names working, and when I'm ready, I'll re-direct clarendon.org (my primary domain) to clarendonalliance.org. How do I do that? When people talk about subdomains and subdirectories, I find that confusing, so if you can use and example in your explanation, that would be a big help. Thanks in advance....