Genealogy research in New Zealand can seem a bit difficult when you first attempt it because, unlike many countries, there is no large genealogy related website that ties all the various historical records together (such as Ancestry.com).
Unfortunately the New Zealand Census returns were not kept. However there are other resources available such as Wises Postal Directories, Electoral Rolls, Cemetery records, School rolls, Return of the Freeholders, Sheep Returns and the like. The problem is, few of these records are available online.
One recent boon for those researching ancestors from New Zealand is the "Birth, Death and Marriage Historical Records" online search made available by the government of New Zealand.
Historical records mean information relating to:
1. Births that occurred at least 100 years ago
2. Stillbirths that occurred at least 50 years ago
3. Marriages and eventually Civil Unions that occurred 80 years ago
4. Deaths that occurred at least 50 years ago or the deceased's date of birth was at least 80 years ago.
An example of how this database can help you:
You know that your great-grandmother, Lillian, maiden name Henley, was born about 1880 in New Zealand. Go to the Birth search section, type in the surname Henley (don't type in her first name) and give a year range of 1870-1890. Find Lillian among the names displayed. If her parents names are listed, look to see if other children in your search results had the same parents.
Now you should have the exact birth year of your great-grandmother, hopefully names of your great-great grandparents, and possibly the names of some of their other children. Assuming that they got married a few years before the oldest child on your list, go to the marriage search page and type Henley in the GROOMS surname box and enter a year range of 5-10 years. If he shows up in the search results, your great-great grandmothers maiden name will be provided.
Now you want to know if your great-great grandparents were born in New Zealand. Assume they were 15-25 years old when they got married and go back to the birth search page and try to find them.
Bouncing back and forth between the birth, marriage and death search pages, you can quickly add to your family tree.