Out of the box your paper is read at your-desk.newsroomfloor.com. To read it at your own address you type the address into your desk, add one record at your registrar, and it serves; the certificate is ours to handle. Your built-in address keeps working either way, so no link ever breaks.
Open Your own domain on the Admin tab and type the address under Your own address. The page decides which of the two lanes DNS allows, asks the edge for the address, and prints the one record with its real values. It then re-reads the domain each time it renders, and the floor re-reads every pending domain every five minutes on its own, so it goes live whether or not you come back.
For news.example.org when example.org stays wherever it is today.
For example.org itself, with nothing in front of it. It is as simple as a subdomain. You keep your own DNS zone and your own email, and you change one record and nothing else.
When a paper is read at more than one address, the primary address is the one search engines treat as the original. It is not set by default, so each address is its own canonical. Once your domain serves, set it under Desk settings, General, Primary domain, so the paper does not split its ranking between two addresses.
Questions go to support@drm3.io.