At the top, centre of the screen is a drop-down menu > click to open a list of your devices.
Or open the Find My iPhone app on another iOS device. Track, Lock & Erase your iPhone with Find My iPhone Please note: if you believe your iPhone has been stolen, do not attempt to recover it. In the event you’ve lost your iPhone, or it has been stolen, take these steps to have a better chance of securing your data and possibly recover your device.