Since you have the IP of the internet address of the router you must ask them to FORWARD the PORTS that remote access uses. I decline to duplicate web content about which ports are required (this is something you must burn into your brain or write in your support notes.) But do look at http://portforward.com/ if you need to cheat on the setup.
To recap: configure that router to forward the remote access ports to that machine you need to get access to. Remember this is a HUGE SECURITY RISK since most machines leave the Administrator logon with NO PASSWORD. Be sure they have a complete backup before exposing this machine to the internet.
I never use remote access but turn to secure versions of VNC.
Oki have no idea where to start
i would like to acces another system over the net, i have the IP address of the system and the IP and user name etc of the Router
where do i start please
i have remote acces turned on in windows etc