WSJF is about prioritisation of different Epics. The Framework tries to separate Business Value from Time Value and Risk / Opportunity Value. At the end you get a Cost of Delay based prio.
What is it about:
http://www.agilenotanarchy.com/2014/08/getting-from-theory-to-practice-with.html
Material for a Workshop:
http://www.safeleadershipretreat.com/safe-city-simulation/