How can I get over my fear of the supernatural and unknown?

Ghosts, spirits, demons, even spirit guides... whenever I hear about them I start getting paranoid, especially if it's at night. For some reason I start looking towards my bathroom on my left, and it's all dark and stuff, so I get up and close the door. I get spooked out very easily, and I hate it. I guess it comes from a somewhat "trauma" when I was 10 when I looked at a scary website on a public library computer with some boys my age. It didn't seem scary then because it was daytime and we were laughing inside a library, but when I came home I got intensely terrified and stayed that way for a month. Ever since then, I can't handle too much spooky stuff that deals with superstitions, myths, and legends. Maybe it also has to do with mankind's fear of the unknown, but can someone PLEASE advise me on how to reduce my fear? It's almost approaching phobia level!