Site already created in multisite as subsite.

I have a multisite WordPress installation. I have my main website at I have another site I am building at I have installed everything correctly with Multi-Domain, however it seems there is NO information about how to move this site that has ALREADY been created, to a domain ( added through Multi-Domain. I can create a new site with this new domain, but don't know how to make the site at /cosmicdew work as this new domain.

This seems like a very simple way to use this program, something that many would use it for. Why is there no information on this? Is it just not possible?
All I want to do is have the site I've already started working on at to work as, which has already been added successfully though Multi-Domain. (It would also help if your plugin list was sorted alphabetically in the drop down on this form.)