ADSL routers usually do not provide the public users (Internet) to access the LAN it is connected to internaly. This is purely for security reasons since an improper configuration could cause a major security hole.
More advanced models might allow you to configure the device to allow the Internet to access machines on your lan, but you need to check your users manual to see if this is possible with the model you have purchased.
Usually this access is possible via port mapping which is done via a web interface that's loaded from the router. There you can map specific ports to internal machines on your network, for example, you can map the public ip of your router and port 80 (http) to your workstation's IP address internally and port 80, so when someone from the Internet tries to access your router on port 80, they are redirected to your workstation's webserver.
Again, check the documents that came with the router to see if this is possible. Also keep in mind that since your on dynamic IP, you might need to constantly update the router's configuration everytime its public IP changes.