i have 3 computer connected to a router (d-link di-604) i need to connect through my computer from an other house through the internet my modem ip is 77.xx.xx.xx
my computer ip is 192.xx.xx.102.
I think the problem i encounter is when i type ssh 77.xx.xx.xx it get to the router but then does not know which computer to go to.
the router was setup by my downstairs neibhor while he still had windows (before i installed slackware) the network is fine from within but i am not able to connect from outside.
i never work with a router before i am therefor quite lost here.
Any help is welcome.

Once you login to the router's administration pages you should see a section called nat or port forwarding. Just enter 22 in the port box and the 192 address of your server into the ip address box.