I am sure that you are familiar with the Holy Trinity.
(The Father, Son, and Holy Spirit.)
The father created the son to fulfill the prophecies he has given to prophets to track down in documents that you can view as the books of the bible today.
When Jesus was gone, then who would teach the upcoming followers?
The Holy Spirit is the spirit of Jesus upon the believer.
It is supernatural and I can not explain how it communicates. It just does.
It communicates to the Pastors and Evangelists so the message will be given on Sunday Service at Church or just about any other time. This way the Christians can have one on one training to become better people just like the disciples did when Jesus in person gave Sermons.