I saw a ghost in my brothers room, what do I do if i see it again?

If you see it again, just do the same thing. And what Chaos said, about using a wigi board-- don't do it. Wigi boards are dangerous things which should not be messed with. If you use a wigi board, it opens up a portal to the other side. When no one is home but you, get a digital voice recorder and hold an EVP(Electronic Voice Phenomena) session, ask it questions like "Who are you?", "What are you doing here?", "Why are you here?" etc. etc., and wait about 10+ seconds until you ask another question.