|Ok you're actually managing to confuse me.|
Typical setup is as follows:
Internet >> SOHO Router >> Clients/Servers
Note, most SOHO Routers have 4 LAN ports. If you have more than 4 clients/servers then you need to add a switch and it looks as follows:
Internet >> SOHO Router >> Switch >> Clients/Servers
Once you have your router plugged in, you need to open a web browser and connect to it's management interface by putting the routers default IP address in the URL field of the browser.
Once connected, you'll have to login. Login and IP details will be in the setup guide.
Once logged in, go to the WAN setup and put your static IP settings, as provided by your ISP, into the WAN side of the router.
Then you should be able to connect to the internet.
If that's working, then you're ready to do the port forward.
First a couple details. In the case of a server, you should always use a static IP so it can never change. Most SOHO routers by default have a DHCP scope of 100 to 199 so choose an IP for your server that is not in that range. I would use something like .10 myself
Router IP = 192.168.0.1
DHCP Scope = 192.168.0.100 to 192.168.0.199
Give your server: 192.168.0.10 with Gateway IP: 192.168.0.1 (the router is the gateway).
Once your server has it's IP statically assigned and it's communicating on the internet properly you will want to create your port forward.
Again, connected to the router's management interface find the port forward section and setup a port forward. As I said previously (using the example IP I just mentioned above) the forward would look as follows:
Forward Port 3389 to 192.168.0.10
Once you have your server setup to allow RDC sessions to connect to it, you should then be able to connect remotely using RDC on whatever laptop/PC you're using at that moment in time.