New to Ubuntu

[mahesh]

Hello.. I am a newby to ubuntu and trying to get an ssh remote server access setup/established so I can have remote access for software installation/updates while working from my office computer.
I have successfully installed Ubuntu and setup OpenSSH and have confirmed the system is "listening".
I am able to remote access through "Putty" while on the same LAN/WAN (router), but continue to be "timed out" when trying to connect from outside of my network (router).

Any detailed directions/recommendations would be very much appreciated.