You must find a tutor of that Working who is willing to teach you. Both student and teacher must spend an out-of-game downtime action on instruction for you to learn the new Greater Working. The tutor may be a player or NPC and does not have to be capable of casting it in order to teach. You may also use Scholarship to research your own in downtime actions.
How do I learn a new Greater Working?
About the Author: Fractured Larp
Fractured is a “survival” LARP with dark fantasy and horrific elements presenting a diverse array of character possibilities. Our setting and rules system promote a game where disparate and often alien peoples are forced by circumstance to stand by one another for the purpose of continued survival. The setting is as mysterious and player-responsive as you make it.