But how in the hell do you actually use it? How do you know its working, and not just you moving the planchet?
The clinical term is "ideomotor response." You may not realize that you are moving the message indicator, but you are. This is similar to automatic writing, also known as automatism, a well-understood psychological phenomenon. Clearly, some persons of a religious nature view Ouija boards as evil. Many movies and TV shows have been made around that theme. So you need first of all to decide whether you believe in such nonsense.
At a more human level, let's consider how a Ouija board works. Vibrations from the finger tips move the pointer about the board, spelling out answers to different questions. So what the Ouija board becomes is a key which can unlock contents of the unconscious. This is always an undertaking to be taken with great caution since the contents of the unconscious mind can be volatile and easily misunderstood.
Further, Ouija boards can set up what are known as "self- fulfilling prophecies." Let's suppose you ask the Ouija board whom you will date and the you spell out "Mary" or "Bud" for reasons which your unconscious understands. Then you might be on the alert for persons with this name coming into your life, perhaps missing in the meantime other opportunities. In any case, along comes a Mary or a Bud and you jump at the opportunity to go out with them, something you might not have considered were it not for the Ouija board. But the reason you go out with them is not because the Ouija board predicted it but because you were expecting it to happen!
Also decide first what you would like the Ouija board to do for you. Ouija boards have an interesting way of reflecting the mental attitudes of the users by responding accordingly. If you want it to act wacky, or have it scare your pants off, the Ouija will not disappoint. If, however, you are looking for a meaningful experience, the Ouija board can offer that also. It's completely up to you.