I have configured RADMIN3.4 as instructed but it seems that going at the system tray and hovering the mouse over shows the internal ip address that the wireless router assigned. It does not connect even when i followed the instructions. I have even configured AVAST to allow both remote and local IP addresses and port 4899 but still it does not connect.
The outside world will need to know your external IP of your router. If you have a dynamic IP you might look at dynamic dns from someone like zoneedit.com
In the router you should be able to set up port forwarding for ftp port 21. On my linksys router it's simple, go to the forwarding setup page, identify the port, and direct the port to the internal IP address of the server.
Once you enable this, ftp from outside will automatically be routed to the internal server ip address.