Confirmation is the outpouring of the Holy Spirit as received by the Apostles at Pentecost. It "imprints on the soul an indelible spiritual mark, the 'character,' which is the sign that Jesus Christ has marked a Christian with the seal of the Spirit by clothing him with power from on high so that he may be his witness. (Catechism of the Catholic Church 1304). Through this Sacrament, Christ also gives us the grace and strength to live this new mission and identity well:

• It strengthens our relationship as sons and daughters of God the Father.
• It strengthens our bond with Christ.
• It helps us grow in the Gifts of the Holy Spirit.
• It makes us more perfect members of the Church.
• It gives us special strength to witness to the Gospel and to accept the cross (see Catechism of the Catholic Church, 1303). 

What Confirmation is is much more exciting than what it isn't. It isn't Catholic graduation. It isn't becoming adults in the Church. It isn't a rite of passage. It certainly isn't when we choose for ourselves whether we believe in the faith or not. All of these things sound like things to say when we don't know what to say, right?

It is a sacrament, where, through visible signs, God makes invisible changes in our souls, and gives us the grace to live out our new identity. 

Christ promised that the Holy Spirit would come upon His disciples in a special outpouring. We see the Holy Spirit come upon the Apostles at Pentecost, but we're still waiting for it. While we are brought into the life of the Trinity at Baptism, the sacrament of Confirmation is God making good on that promise of a special outpouring. It may not seem as dramatic as Pentecost, but it can be: God will pour His Spirit into our lives to the same degree that we can receive Him.

Your children will follow your example more than anyone else's. But that example has to go beyond the externals. They might see you go to Mass; they might see you go to Confession; they might see you pray; those things are good and necessary if you want them to take their faith seriously. But they need to see that the faith is more than the externals: they need to hear what the faith means to you. They need to hear why you do these things. They need to hear about your relationship with God, wherever it is. You don't need to be a saint. But let them see that you want to be a saint, and they will want to be saints also.

Also, you should fill out the forms, drive them around, and whatnot. That's important, too, I suppose :)