I'm starting to work through the Lightning Components Developer Guide working my own developer org where I've created a name space.

But I'm confused about how to do this in our real development stream.  We have a production org and some sandboxes we do development in.  (We develop in sandboxes instead of individual developer orgs as we need common data that is setup for all developers and there's no way we could maintain it in several individual developer's org.)

In out production org and in our sandboxes, there is no "Edit" button to allow specification of Namespace on the Packages page.

So I'm unclear how to reserve a namespace.  Any clue? 

We do have a domain name registered.  Does it have something to do with that?