Above the text in your post, there's a bar of... thingies. Buttons. One of them is a yellow smiley face. Next to it there's a picture and next to that is a media button. To the right of that, there's another button - that's the one you click, then a menu comes down. Choose Spoiler and put the title in. Then the contents go between the [SPOILERs.
Once upon a time, the actor for Fred Weasley read the last part of The Deathly Hallows on a train. A man came up to him and asked him for his ticket. He said, "Leave me alone I just died!" I feel like that right now.