Addon:
http://www.curse.com/addons/wow/malkorok-helperThe AI mode might not be 100% functional, so I suggest still having someone to mark (on the addon). You simply left click a section to make it red - everyone in the raid will then see it.
Do not stand right next to a red zone, you might still get hitDo not stand too close to the center while in a safe zone, you might still get hitStay in the middle of the green zone and you'll live - I've never died to this mechanic when I stood in the middle of the green zone