Please make sure everyone starts this questline and you're on the step where you need sigils of wisdom and sigils of power. You get these from LFR boss mobs + flex boss mobs.

http://www.wowhead.com/news=217993/mists-of-pandaria-legendary-cape-guide-updated-for-5-4

that should be a semi guide to let you know what you need to do the questline.