The ministry of Lector is an important role in the Mass. They proclaim the first and second readings from scripture, and when necessary, the psalm. In addition they announce the intentions. There are several resources available to assist Lectors in preparing for their role.
From the General Instructions of the Roman Missal:
The Functions of the Reader
194. In the procession to the altar, in the absence of a Deacon, the reader, wearing approved attire, may carry the Book of the Gospels, slightly elevated. In that case, the reader walks in front of the Priest but otherwise walks along with the other ministers.
195. Upon reaching the altar, the reader makes a profound bow with the others. If he is carrying the Book of the Gospels, he approaches the altar and places the Book of the Gospels upon it. Then the reader takes his own place in the sanctuary with the other ministers.
The Liturgy of the Word
196. The reader reads from the ambo the readings that precede the Gospel. In the absence of a psalmist, the reader may also proclaim the Responsorial Psalm after the First Reading.
197. In the absence of a Deacon, the reader, after the introduction by the Priest, may announce the intentions of the Universal Prayer from the ambo.
198. If there is no singing at the Entrance or at Communion and the antiphons given in the Missal are not recited by the faithful, the reader may read them at an appropriate time (cf. nos. 48, 87).