After your Gateway Puck is connected to your WiFi network, you will enter Setup Mode. Setup Mode will list devices and allow you to assign them to rooms. You will also be able to assign integrated Smart Thermostats and IR-controlled devices to rooms.
After you have connected your devices and assigned them to rooms, scroll to the bottom of the page and click Done with Setup.
Any remaining required steps will be shown on the App home screen if you have forgotten to complete them during setup.