The holy spirit

We learned about the holy spirit in the VISA course. I have completely misunderstood about it. I had thought the holy spirit was like angel, but actually that was human. Also they taught me that God is one and also God is three. It was very hard to understand, but it was very attractive as well. All of us have the holy spirit, and he always helps us to understand about the Bible and Jesus. And Christian is always inviting him, it is the difference between me and Christian. I am still confused about that.