Let's continue reading Verbum Domini, picking up from "The word of God and the Holy Spirit" to the end of the first section.
Jesus is not a word of God but the Word of God. Singular. The Holy Father quotes St. John of the Cross, telling us that "(God) spoke everything at once in this sole word - and he has no more to say... he has spoken all at once by giving us this All who is his Son."
What of the Holy Spirit, then? The Holy Spirit spoke through the prophets and inspired the authors of the written word of God. He sustains the Church. Pope Benedict seems to be telling us that the Holy Spirit works to express, clarify, and spread the one definitive revelation of Christ.
Without the Holy Spirit, we would have the Word of God but not be able to understand it. "(W)ithout the efficacious work of the 'Spirit of Truth', the words of the Lord cannot be understood." I can give my child a book, but I must also teach him to read.
The Spirit acts to spread the Word and help us understand Him through the Church. The Holy Spirit inspired the prophets and apostles, and now guides our mother Church. Unless we cross that "pneumatalogical horizon", we have no hope of really understanding the Word of God! So many Christians have the book but won't let their mother teach them to read.
There are far more lessons a parent teaches by spoken word and by action then by a written book. Our mother, the Church, under the guidance of the Holy Spirit, has taught by word and action for two thousand years. It is "important...for the People of God to be properly taught and trained to approach the sacred Scriptures in relation to the Church's living Tradition, and to recognize in them the very word of God."
Read Acts 8:26-35. We can be confident in our understanding of Sacred Scripture because we have the Church to guide us, and the Holy Spirit guiding the Church. If the homilies at your Masses don't often focus on Scripture, or if you want to supplement with even more teaching from the Church, you can find excellent homilies online. I recommend both Fr. Larry Richards and Fr. Robert Barron.