If you want to research your genealogy it is easiest to start with yourself and your immediate family. Note down your birth date, the details of your siblings, and then your parents. This can be done in written notes and/or a family tree diagram. Once you've completed your immediate family you can then add in your parents' siblings - your uncles and aunts. With each of those try and find out who they married and when, then add who their children are and when they too were born.
From there you can go back further in time to your grandparents - that is your parents' parents and their siblings and build it up from there.
Once you get to the point where your parent's and other living extended family members can't tell you any more about your ancestors you may then need to start researching information from other sources. In New Zealand and throughout the Commonwealth many local governments such as District and City Councils have cemetery records online.
Here are a few New Zealand examples you can try putting your surname into. The The Tararua District Council and the Wellington City Council in the North Island and the Christchurch City Council in the South Island.