It's hard to describe it to someone who has no experience of it. You could put it very simply, and say you have a mood disorder (depression, bipolar, whatever it is) plus some hallucinations and paranoid thoughts. Or you could just keep it to yourself, and only share what is relevant at the time to people you trust. I find that most people don't get it anyway. My brother sort of gets it, my father definitely doesn't. Just don't let it weigh you down... you're the same person you always were. You'll be okay.