Catherine Fitzpatrick’s marriage was registered in Banbridge on 21st November 1923. You can view the original certificate on-line on the GRONI website, using the “search registrations” option:
https://geni.nidirect.gov.uk
You will need to open an account and buy some credits. It costs £2 (sterling) to a view a certificate. That certificate should give you information to trace the families back eg the family townland.
Here’s a family in the 1901 census that might be Catherine’s (Ballyvarley is within Banbridge registration area) but you need to get that marriage cert to investigate further:
http://www.census.nationalarchives.ie/pages/1901/Down/Scarva/Ballyvarley/1208257/
1911:
http://www.census.nationalarchives.ie/pages/1911/Down/Scarva/Ballyvarlay/209699/
Probate extract from PRONI wills site:
Probate of the Will of Bernard Fitzpatrick late of Ballyvarley County Down Farmer who died 28 August 1914 granted at Belfast to Catherine Fitzpatrick the Widow Patrick Fitzpatrick Farmer and Patrick Digney Farmer.
The will itself is in PRONI in paper format.