You create a passage, give it the name StoryCaption, then put whatever you want to be shown in there. Like:
Health: $health Mana: $mana
@Brugtz
It is the unique passage name of each of the special passages that makes them special and what causes them to automatically behave as specified in the documentation, which is why the spelling and letter casing (upper and lower case) of each of those passage names needs to be exactly the same as it is stated in the documentation.