The earliest RC records for Templemore are for St Columb?s, Derry. However taptisms and marriages only start in 1823. So you are not going to find the 2 baptisms, if that?s where they were born. You might just find their marriage. (Don?t expect too much from the marriage record if you do find it. Normally all you will get are the couples names, the date and their 2 witnesses. (No addresses or parents names. And the records will probably be in Latin.).
The records are on-line on the rootsireland site (subscription) and there is also a copy on microfilm in PRONI, Belfast and the National Library, Dublin. (Both are free to view but require a personal visit to access them).
Very few RC parishes in the Derry area have records much before the 1820s and so research for the late 1700s/early 1800s is often nigh on impoissible.