Using Kssh or ssh

I have a Lan (five machines)connected to the Internet through a router and cable modem. I'm trying to connet from my friends Lan to MyaceJ.site on my Lan. In the kssh window the IP address to my cable modem is what I put for host and for user name in the kssh window I put my user name on Myacej.site. In the kssh window I have X11 enabled, but that doesn't work. I understand that my external IP address is not a Host. So what should I use for host? Not MyaceJ.site because that machine is on the Lan behind the modem and router. So how do I do this? How do I connect to Myacej.site in this case? I'll use ssh if someone tells me how to get past the cable modem and router to Myacej.site. Thanks, Jerome