If you’ve purchased a custom domain from wordpress.org you’re in the wrong place. You’ll need to go to the wordpress.org support forums, we have a different software and will not be able to give you correct answers.
Hold on. WordPress.ORG does not sell domains. He is probably hosted here and thus in the correct forum. But the way to tell is for us to get a direct link to the blog, starting with http. Without that, we are only guessing.