The Church teaches four important dogmas about Mary. First, Mary is the Mother of God. This tells us that he child Who took on her flesh was the Father's eternal Son, the Second Person of the Trinity. Hence, Mary is truly the Mother of God.
Second, Mary was Immaculately Conceived, meaning that she was conceived full of grace, without original sin. To become the mother of the Savior, Mary was endowed with this unique gift so that she might be a pure vessel for the Son of God. By the grace of God, Mary remained free from sin for her whole life.
Third, the perpetual virginity of Mary. Mary conceived Jesus as a virgin by the power of the Holy Spirit -- and this points to Jesus's divine origins as the Son of God who truly entered our humanity. Her remaining a virgin throughout her life serves as a sign of her exemplary faith, her undivided gift of herself to God's will.
Fourth, Mary's Assumption. At the end of her earthly life, she was given the unique privilege of being assumed body and soul into Heaven, anticipating the resurrection of all Christ's faithful at the end of time.
Mary is the spiritual mother for all Christians. Because of her complete cooperation with Jesus's redemptive work, she continually intercedes on our behalf before her Son.
Catholics don't worship Mary and the saints like we worship God, by we honor them as models we can imitate, and we recognize the great work God has accomplished in their lives.
Catholics don't pray to Mary and the saints like we pray to God, but we seek their intercession, asking them to pray for our needs just like we might ask a friend to pray for us.
The attention we give to Mary and the saints does not distract from our relationship with God, but draws us closer to Him -- for just as Christian communion draws us closer to Christ, so does our communion with the saints join us ever closer to Jesus.