Wigan Genealogy

Looking for information on my Grandad William Nearys family. His parents names were Thomas Neary and Ann McGuirk.They were born between 1842/46 somewhere in Ireland. Various addresses - Cambridge St. Bradshawgate. Greenhough Row, which I think was off Hardybutts. His great grandparents were Thomas and Catherine, born circa 1820/21 in Ireland. My grandad was born in Wigan. He lived at 24 Dean Street. any information would be greatly received. I would love to know how to go about finding out where in Ireland, when they came over to England, and how they ended up in Wigan.