I added the spoilers for you this time but you have do it from next time. For using spoiler you have to use the syntax without the underscores, also they should not be replaced by space, they need to be just removed.[_spoil_]your text[_/spoil_]

Or else simply you can use the button for spoilers after selecting the text you want under it. The button is white square while your are posting using advanced editor (that is full editor when you make a new thread)