How do I talk to my family?

I have always been ridiculously afraid of the dark, but never thought anything of it. However I can't even sit in a quiet room because I hear awful noises. Just hissing, hardly ever words, and if so its just my name. I sleep with my tv on and a lamp but am STILL paranoid. If I walk to my garage alone I run full speed back in the house because I'm that afraid. I don't even know what I'm afraid of. How do I go about telling my family these things (I'm fifteen so it's necessary that I tell them so I can get help)