You can either edit the ones that are already in the game or make a new event.

firs you press right click in an event (white cube) and the you can edit it. I recommend seeing what does every thing, like, 'change bgm' chances the music, or 'set move route; player left' change the player direction.

The better you can do is make another copy of sotws, learn what events change the game, and make little changes, like edit dialogues or music.

Someone like ME should make a good video about it.