New Zealand recognises copyright in a wide range of creative and industrial works. Any time something is drawn, written, photographed, filmed or recorded, etc, copyright is automatically created. This includes software code and functional industrial designs.
You need to keep your own records of who created what, and when.
To warn others that you have copyright, you should mark it “©2015 Full Legal Name”.
If you create copyright works for others, you need to make sure the ownership is clearly documented.
The rules are different overseas (even in Australia), so if you are exporting, you need to consider your Overseas IP.