You could always get no-ip from www.no-ip.com which will give you an easy to use domain name instead of having to remember the ip address.

Also in windows server you can install IIS, then conect to your pc with port https://yourip:8098 then click on manage and remote desktop

I use the dmz host option to forward all requests from the internet to the same pc as it saves having to open certain ports.

OK you have a PC with an external connection (ie your Internet with your ISP) you are normally given a static IP address (more or less) by your ISP. You need to make a note of that address. You also need to configure the PC you want to connect to with Remote Desktop enabled to accept incoming connections.

You then set up your router to forward any packets with the port 3389 to that PC otherwise it will reject any packets and it won't work. Download the Rmote Desktop from Microsoft if using a client before WIndows XP. Connect using the IP address of your ISP and it should connect to that computer. If you want to connect to others, while not messing around with NAT and ports, you could always when connected to your home PC use the Remote Desktop from that PC (which you are connected to) to connect to another PC :)

HTH.