This sounds like "higher math"...Put the word spoiler inside square brackets -  - in front of what you want to hide and the same thing with an / between the [ and s after what you want to hide. (Maybe start with a test.)
Edit-Looks like I had put too much and spoiled what I wanted to show. It also looks like if you want to hid the whole thing, you don't need the "/" one at the end. Only need that if you want to continue to write normally afterwards.