The Apple Watch app
The Apple Watch app (installed with iOS 8.2 on iPhone 5 and newer) allows you to pair and sync your Watch with the iPhone and to customise some basic settings. When you open it, you’re greeted by an introductory screen which prompts you to pair your Watch with your iPhone. Tapping ‘Start Pairing’ takes you to a screen where you can use the iPhone’s camera to pair the phone with an Apple Watch. You need to hold the Watch up to the camera and align its display with the viewfinder to pair the devices.
There’s also an option to pair manually, which takes you to a more traditional list of devices for you to identify your Apple Watch. To find out your Watch’s name, you tap on the ‘i’ icon on the Watch and then correspondingly select that name from the nearby devices listed in your iPhone’s Apple Watch app.