John the apostle was one of closest associates of Jesus Christ. He was personally taught by Jesus for three years. He was also one of the three disciples that were closest to Jesus. As such, John was present during moments in the life of Jesus when the other disciples were not. During his time as a disciple of Jesus, John received the opportunity to learn from God Himself.
When John wrote his first epistle, he informed his readers that he was passing on a message. He informs his audience that he is passing on the same message that he heard from God. Whether John was informed of this through the teachings of Jesus or through the Holy Spirit one can speculate. However, what is clear is that John was passing on a message that he had received from God.
This is relevant for us today. As Christians, we are taught by the Holy Spirit. Whenever we are taught, we should obey the Holy Spirit by making necessary changes in our own lives. After this, we should pass on the message.
I suppose that the best way to summarize this is: We do not only have a right to pass on what we are taught by the Holy Spirit. We have a responsibility to obey His promptings and to pass on the messages that He has given. In this way, we declare the message that God has given us to those with whom we come in contact. In this way, we can be used by God to build His Kingdom.