Ok, on a solid state relay you have 4 tabs, 1-2 are for switching the live (black) from your router, the tab3-4 are to control the relay from 3-32v.(*Note solid-state relays are polarised, you have tab 3 (+) and tab 4 (-) ).
You wire the gnd from your parallel port to the tab 4 (-) and the signal wire to the tab 3 (+).I'm using pin 16 to control my router depending of your software setup.
I'f you have another question, let me know.
Thanks,
Alex
www.aghobby.com