I just joined a faction, and in order to begin, I need to register at their website. Well, they said they would send me my information in an e-mail to my registered Darkness account. What's Darkness, and where is it?
"Darkness" is the name given to the new SWC site design when it was in development about, oh, 7 years ago. Usually it is only used now in referring to messages sent via the system here on the site, known as "Darkness Messages" (or DM for short).
In other words, they'll be sending the information to the e-mail you have listed here on SWC.
"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."