Enable RDP on your computer.
Enable the RDP exception within your Windows Firewall if the firewall is on.
Within your Prosafe Router you want to enable Port Forwarding. 3389 is the default port for RDP. Point any traffic coming in from 3389 to forward to the internal/private IP address of your computer (probably 192.168.x.x).
To access your computer via RDP from another computer with internet access you would open RDP and type in your public IP address and the port number, example: 172.15.34.105:3389
This will tell the RDP session to connect to the IP address using port 3389.
Other remote desktop programs may use other ports. In that case you will need to have those ports forwarded. If you want to get more technical, you can adjust the ports to slightly increase security.