Configuration issue or locked Brain

Hi Everyone,

Time to expose my ignorance, I have looked for a tutorial for two days now and can’t seem to find an answer to possibly the most simple question.

I am trying to configure w3tc with Rackspace Cloud, I have built the container. not a problem there.

When I get to the next part is where my brain is frozen.

Replace site’s hostname with:
the container # .cloudfiles.rackspacecloud.com or CNAME:

Then next there are boxes to put different cnames

Where do I replace “sites hostname and with what?
How do I configure the Cname part under that line?

I apologize for my ignorance but have found nothing so far to direct me in this part of the process.

I truly appreciate your time.