The Ministry Of Health-Manatū Hauora has a web site with the latest updates, information and advice on COVID-19:
COVID-19 (novel coronavirus)
https://www.health.govt.nz/our-work/diseases-and-conditions/covid-19-novel-coronavirus
The site has very comprehensive advice for anyone planning a public event (indoors or outdoors):
COVID-19 - Advice for public events and mass gatherings