For example, the first miracle which Jesus works is not a physical healing, but the tranformation of water into wine, which prefigures the later transubstantiation of wine into the body and blood of Jesus. Paul Haffner, in his book The Sacramental Mystery, writes that the Last Supper is like the wedding feast celebrating the wedding of Christ to His Church.
Did Jesus perform the miracle only that His disciples would believe, or did He also perform it because His mother asked him to do so? The wedding at Cana shows us that Mary was at both the beginning of Jesus' ministry, as she will be at the end, when she stands at the foot of the cross at Calvary. As Mary provides a model of humanity to us, we should take her words to "Do whatever he tells you" to heart.
The Catholic Catechism #1335 states: The miracles of the multiplication of the loaves, when the Lord says the blessing, breaks and distributes the loaves through his disciples to feed the multitude, prefigure the superabundance of this unique bread of his Eucharist. The sign of water turned into wine at Cana already announces the Hour of Jesus' glorification. It makes manifest the fulfillment of the wedding feast in the Father's kingdom, where the faithful will drink the new wine that has become the Blood of Christ.
Scroll down almost to the bottom of this page, and you can read Scott Hahn's remarks on John 2.
Of course, we should go to John 2. The first of the seven signs in the Book of Signs, the fourth gospel. The first of Jesus' miracles is to turn water into wine, just as the first miracle of Moses was to turn water into blood, so Jesus turns it into the blood of the grape as it is called in Genesis 49. Here we have, I believe, something that is fraught with all kinds of rich literary and theological symbolism. In John 1, "Behold the Lamb of God who takes away the sins of the world," says John the Baptist. In John 2, the Lamb goes up to a wedding feast. Now does that sound familiar? A wedding feast where a lamb attends? That's how John is going to climax his book of Revelation, by inviting all of us to the wedding supper of the Lamb. And then along with the wedding banquet of the Lamb, we are also going to be introduced to a Virgin Mother Queen's city, the new Jerusalem, which is both virginally pure but maternally fruitful.
It is also worth mentioning, that the Catholic Church considers the wedding at Cana to be the time when Jesus elevated marriage to a sacrament.
CCC paragraph #1613: On the threshold of his public life Jesus performs his first sign—at his mother's request—during a wedding feast. The Church attaches great importance to Jesus' presence at the wedding at Cana. She sees in it the confirmation of the goodness of marriage and the proclamation that thenceforth marriage will be an efficacious sign of Christ's presence.