The key site for legislation and case law for the Pacific Region is PacLII www.paclii.org.
For regional resources, including journals, law reform, and research guides try the Pacific Legal Gateway http://www.paclii.org/gateway
For Legislation past and present for the Cook Islands, see: The Laws of the Cook Islands.
These articles about finding Pacific Law are useful.
Ruth Bird has written Law of the Pacific Islands: A Guide to Web Based Resources (April 2005).
Peter Murgatroyd has written an Introduction to researching South Pacific Law 2022.
Also search online for Pacific Law guides produced by other University Libraries in Australasia.
There are general guides to legal research in the Law Library at and around K79. Some of these are specifically for Australia, for example Sue Milne's Practical guide to legal research (Law K79 MM856).
Online guides will link you to other research material as well as to primary sources. Start with these ones: