1. Modern servers use a protocol called "remote management" instead of the old "remote desktop".
2. In order to reach the server from a different machine across any type of dot network you first have to punch a hole in the firewalls * so that the two machines can conduct a handshake protocol… in most cases you use the "dcomcnfg" commands to do it but some retards just disable their dot security all together.
* To be clear, You need to do this on both the server and the machine (which is usually a laptop now days) remote managing it.
3. That gets the two talking but not over the internet… for that you need a way to resolve the name into an ip address the internet will accept. Different countries allow or restrict what you can do but generally you need some kind of "static| dynamic name to ip address"… i.e. a business dns.
p.s for private or small business usage, a workgroup is MUCH easier to set up and considerably less overhead than a domain but ime once you have more than ten users it becomes much of a muchness.