You will be required to apply for a Marriage Licence, through Births, Deaths and Marriage http://www.dia.govt.nz/diawebsite.nsf/wpg_URL/Services-Births-Deaths-and-Marriages-How-to-Get-a-Marriage-Licence
Your licence is valid for three months from the date of the licence and a Registered Marriage Celebrant is required to carry out the marriage.
In the 21st century a lot has changed with marriage ceremonies except at some point you are required to say “I AB take you CD” to be my husband/wife – or words to that effect, using the full names of the couple.
The rest of the ceremony can be personalised to suit the couple. Two witnesses are needed – they do not need to be the bridal couple, they can be anyone that you nominate.
The marriage licence is signed by the bridal couple, the two witnesses and the Celebrant. All very straight forward and I am able to assist with any questions.