Here's how it starts [as taken from the Catholic Information Network website]:
I, Patrick, a sinner, a most simple countryman, the least of all the faithful and most contemptible to many, had for father the deacon Calpurnius, son of the late Potitus, a priest, of the settlement [vicus] of Bannavem Taburniae; he had a small villa nearby where I was taken captive. I was at that time about sixteen years of age. I did not, indeed, know the true God; and I was taken into captivity in Ireland with many thousands of people, according to our desserts, for quite drawn away from God, we did not keep his precepts, nor were we obedient to our priests who used to remind us of our salvation. And the Lord brought down on us the fury of his being and scattered us among many nations, even to the ends of the earth, where I, in my smallness, am now to be found among foreigners.To read the rest, click this link, or the one above.
And there the Lord opened my mind to an awareness of my unbelief, in order that, even so late, I might remember my transgressions and turn with all my heart to the Lord my God, who had regard for my insignificance and pitied my youth and ignorance. And he watched over me before I knew him, and before I learned sense or even distinguished between good and evil, and he protected me, and consoled me as a father would his son.
Therefore, indeed, I cannot keep silent, nor would it be proper, so many favours and graces has the Lord deigned to bestow on me in the land of my captivity. For after chastisement from God, and recognizing him, our way to repay him is to exalt him and confess his wonders before every nation under heaven.
If this snippet has whet your appetite for a good, short biography of St. Patrick, try Saint Patrick from the Christian Encounters series.