How to hide spoilers?

[CrimsonEmotions]

Over on the Maiden England tour thread, there is an option to view or not view spoilers. How can I set up the spoilers and hide them when I'm posting?

 

[Crimson Idol]

http://forum.maidenfans.com/threads/how-do-i-mark-something-as-spoilers.23115/

They will automatically hide when posted