Do you know who the real saint Patrick was? Far from an imaginary legend, he was the first influential Christian missionary to Ireland. The Lord Jesus used him to convert thousands of the savage, barbarous, Irish peoples to the worship of Jesus Christ as God and Savior. We thankfully possess Patrick's own autobiography of his life, written shortly before his death in the mid-400s AD. In this account, Patrick describes his prideful youth, his enslavement by so-called "pirates," his captivity in Ireland as a farmer, his time back in Scotland suffering opposition from his community, and finally his journey and ministry in Ireland. Throughout his account, he describes in detail several prophecies he received, and miraculous answers to prayer that enabled him to become the spiritual father of the Irish. If you want to obey Jesus, this reading of his story will encourage and challenge you with his humility, boldness, zeal, and love for people.

Here's a link to his Confession and a brief explanation of his holiday:

Work info: Confession of St. Patrick - Christian Classics Ethereal Library

Who was Saint Patrick and why do we celebrate St. Patrick’s Day? | GotQuestions.org