Searching for my Grandfather's Birth of Baptism Certificate O'Reilly family from Dublin

My grandfather, John Francis O'Reilly was born in Dublin approximately sometime between 1868 to 1872, my Great Grandfather's family name is O'Reilly, and my Great Grandmother's family name is Torme, or Tormey.  My Grandfather died in Puerto Rico in 1945.  That is about all the information I have been able to glean from my few living relatives.  Looking for any available information, or someone who can assist me in the search.

thank you

Philip M Reilly