Yeelight bulbs are automatically discovered and added to hue emulator on light search performed from Hue app. The light must be first connected to the local WiFi network and LAN control must be enabled from the YeeLight app. This can be done from the eject icon located in bottom right corner of the app. If light IP address changes, you need to perform a new light search in order to update the IP address for all the lights. To avoid this, you can give each light a static IP address in your routers settings.