Where are you getting all this?

Where are you getting all this info about lorien and the walkers of sigma? Who are the Triads? Ive seen most episods and ive never seen anything about the Triads? Did it not say that the shadows were the most powerful (they were old when even the ancients were young), rather than the walkers of sigma? Werent the walkers of sigma only in the two episodes (the final battle at corina six and when the whitestar went to look for first ones).

Tell me the names of the episodes so i can watch them.