Once you put the dreamhost nameservers in your GoDaddy account. You will then need to go into your DreamHost Panel and add the domain IE) example.com
While you add the domain, you will be prompted if you want to fully host the domain with dreamhost, which if you're wanting the content to be hosted on dreamhost you want.
You select what directory you want the website to represent, and click fully host.
That's how dreamhost will know that domain is yours.