BOAC
re reading most of the above I think I begin to see the problem, that is you have 6 wire cable which hasnt the same colours and uses as the cat5/rj45 cable that has been referred to but all is not lost. I see that blue and red (or orange) are already used for the telephone connection. next step is to see if any of the other 4 wires are twisted in 2 pairs, if they are connect any pair to the bottom left 2 contacts on your plug next to the orange rectangle and orange triangle, this will become your tx + and - which should be connected to pins 1 and 2 on the rj45 connector going into your router, or what ever your connecting to. the other pair should be connected to the top left 2 connections next to the green rectangle and green triangle rx + and -, the other end will connect to pins 3 and 6 of the rj45 connector.
pc rj45 white/orange pin1 -wall connector bottom left- outofwall - pin1 rj45 router
pc rj45 organge pin2 - wall connector next one up - outofwall - pin2 rj45 router
pc rj45 green/white pin3 - wall connector nextone up - out of wall -pin3 rj45 router
pc rj45 green pin 6 - wall connector top left - outof wall - pin 6 rj45 router
if you cant find any twisted pairs in the telepone cable then just use the wires as you like as long as you end up connecting through a pin1 to a pin1 etc. although without twisted pairs it may suffer in performance.
Hope this helps
Rickity