The Hue nest integration requires any hue installation inside your home with at least one light source. Since Philips Hue communicates with nest via our clouds, you will need to make sure you have created a My Hue account on my.meethue.com and linked it to your bridge. You will also need at least one nest product (nest protect, nest learning thermostat or nest cam) which is properly set with a nest account. If you have what you need to get started then visit nest.meethue.com to set it up.
Once set up, the Hue nest settings runs in the background, making your Hue lights react in a smart way to inputs from the nest system. There are four settings to choose from, once they are enabled they will always be running, waiting for the right occasion to trigger them.