The free registration gives you many benefits, including increased editing options and user preferences. One handy feature is the Watchlist, which makes it easier for you to track changes to pages you are interested in. Another is the ability to create, move or rename pages.
Registration also provides you with a detailed history of all your work in Waihekepedia by associating all your edits to your User name. This is partly for reasons of accountability but it is also helpful from a copyright perspective: if someone wants to use your contributions in a way not allowed under the Waihekepedia copyright, they can ask you on your Talk page, for example. Also, the Creative Commons license used on Waihekepedia encourages giving appropriate credit to authors, and your username is used to give that credit.
To create an account enter all the fields and click on the "Create new Account" button.
See also: Editing Basics