In Part Two of Verbum Domini, in the section "The Liturgy, Privileged Setting For The Word Of God" is a subsection "Sacred Scripture and the Lectionary". In this, the Holy Father emphasizes the importance of the Lectionary and applauds the abundance of Scripture offered at Mass. The Second Vatican Council reformed the Lectionary, he reminds us, and this may lead to a few questions.
First, what is the lectionary? Shouldn't we be reading from the Bible?
We are, of course. The Bible is the whole collection of inspired documents, and passages from the Bible are arranged for convenience in the lectionary. Properly, a "lectionary" is any liturgical book meant to be read aloud during a service, and through Church history such books were produced according to different needs. For example, when books were more costly to produce, the priest's prayers and the choir's antiphons were in their own volumes, rather than take the material and time to duplicate unneeded pages. (Thurston) In our day, we can produce book relatively easily and cheaply, so duplication is not as great a concern.
Our lectionary was introduced March 22, 1970 and contains all of the Mass readings. (Hardon) Scripture is organized by the day to be read, rather than in books and chapters. This applies to the Latin rite of the Church, which includes most - but not all - Catholics. There are other rites, including the extraordinary form of the Latin rite, which follow other rules. (The Holy Father refers to sui iuris (pronounced like soo-ee your-is) Churches that have their own laws. That is, in fact, what "sui iuris" means - their own laws.).
Second, what did the Second Vatican Council (Vatican II) reform about the lectionary?
There is now an "interplay of the Old and New Testament readings". There is an intentional relationship between the readings for a given day, all with Christ at the center. The new lectionary uses a three-year cycle of readings for Sundays and solemn feasts, and a two-year cycle for weekday Masses. Over the course of three years, Catholics hear a large percentage of Scripture as readings (not to mention the Biblical references throughout the rest of the Mass) and the connections between the Old and New Testaments are highlighted. For example, the handing over of the keys of the kingdom to Eliakim (Is 22:19-23) is paired with the handing of the keys to Peter (Mt 16:13-20). That Old Testament reading helps explain the power given to Peter by Christ.
The Holy Father also reminds us of the need to view Scripture as a whole. If we have difficulty seeing the relationship between two readings (or between any two passages), we must find our answer in the whole of the Bible. Scripture does not contradict itself; only interpretations of verses contradict. We should work to resolve difficulties in interpretation "in light of canonical interpretation, that is to say, by referring to the inherent unity of the Bible as a whole." (By "canonical", the Holy Father means "according to the canon" or according to the official, revealed list of the books of the Bible.)
If there are "other problems or difficulties" with the use of the Lectionary that you can't resolve by yourself (or with a few others), then you can do what Jesus said and "take it to the church" (Matt 18:17). Specifically, you would take it to the Congregation for Divine Worship and the Discipline of the Sacraments. This body is the department, so to speak, that oversees the Mass and sacraments, as well as sacramentals, the liturgy of the hours, and the observance of holy days.
Hardon, John. 1999. "Analogy of faith". In The Modern Catholic Dictionary. Inter Mirifica.
Thurston, H. (1910). Lectionary. In The Catholic Encyclopedia. New York: Robert Appleton Company. Retrieved August 2, 2011 from New Advent: http://www.newadvent.org/cathen/09110b.htm