We are no longer associated with Dreamhost, so it doesn't include a hosting account. Where did you read that? I'll need to update the documentation.
But you can use your own domain. Just register and host a domain with any domain re-seller. Most will host a domain for about $1-2 a month.
I like 1and1: https://www.1and1.com/domain-transfer#faq
Then you can update the DNS settings to point to the mycafecommerce server and update your site to use that domain from the admin control panel.