you didn't mention any dates ?
Full civil registration of births, marriages and deaths started here in 1864, and in addition non-Catholic marriages were registered from 1845. An index to these records is available on Ancestry and also free-of-charge on FamilySearch.
For earlier events you have to rely on Church records.
p.s. the town of Ballaghaderreen is in Co. Roscommon (this post is under Sligo)...although at one time the town was divided between counties Mayo and Roscommon.