The novena in preparation of Pentecost is the first and therefore the oldest novena in the Church. It begins the day after the Ascension, which is 40 days after Easter. It commemorates Mary and the apostles waiting in the upper room for the Advocate, the Holy Spirit to come to them. For nine days, they waited. Praying together that Jesus’ promise would be fulfilled. They were scared and not sure what they should do next now that Jesus had ascended to his Father in heaven.
I imagine that they spent time reminding one another of the words he spoke, “When the Advocate comes whom I will send you from the Father, the Spirit of truth that proceeds from the Father, he will testify to me.” (John 15:26); “But I tell you the truth, it is better for you that I go. For if I do not go, the Advocate will not come to you. But if I go, I will send him to you.” (John 16:7)
There are a few sources for a Pentecost Novena.
From Presentation Ministries, there are prayers for each and you read the daily Mass readings as well.
From Pray more Novenas, which you can have delivered to your inbox each day.
From EWTN, the Novena for the Seven Gifts of the Holy Spirit. (This is the one I pray and I’ll post it each day)
No matter which you choose, you are asking for an outpouring of the Holy Spirit in your life. You are asking for the gifts of the Holy Spirit: Wisdom, Understanding, Counsel, Knowledge, Fortitude, Piety and Fear of the Lord are increased as you need. You are praying that the gifts given to you strengthen you and fill you with a holy boldness to do what God needs you to do as his disciple.