Think of it this way.
God created the universe. That means that God is separate and outside the universe. God needed a way to interact with his creation, to become a part of it. That's where Jesus comes in. Jesus is God's avatar here in the cosmos. The Holy Spirit is the link between God and Jesus.
Think of it in video game terms. You are playing a video game. You exist outside of the game. The character inside the video game is Jesus and you direct him via your controller or interface which is like the Holy Spirit.