You first need her parents' names and other details from her marriage cert., which can be bought online:
Registration Number, Groom's Surname, Groom's Given Name(s), Bride's Last Name at Time of Marriage, Bride's Given Name(s), District
14503/1930 DIXON, HENRY G, PAGE, MARGARET E, GRANVILLE

www.bdm.nsw.gov.au/familyHistory/search.htm

Sue