Horror is one of my favorite genres to read and write. But it is not something I would suggest someone else try writing without a bit of basic knowledge about the genre. A Horror 101.
Horror is a genre of emotion. Its readers go into a novel or a short story looking for something that makes turning out the lights scary. That gives them nightmares which keep them awake for days. And the way a writer does this is not by slapping some blood and guts into a story—gore isn’t scary by itself, its gross. But by, if they use gore, making it count.