Before you can start using your Apple Watch, you're going to need to pair it with your iPhone.
The Apple Watch and iPhone may be two distinctly different pieces of hardware, but one can't exist without the other. When you buy a new Apple Watch, turning it on is only the first step — next comes pairing it with an iPhone.
When it comes time to pair your Apple Watch with your iPhone, you'll need to use the Apple Watch app for iOS. You should be able to find it pre-installed on your iPhone (or via the App Store, if you've removed it previously).
How to pair Apple Watch to your iPhoneHow to set up or restore your Apple Watch from a backupHow to get more out of your Apple Watch How to pair Apple Watch to your iPhoneThere are a few ways to pair your Apple Watch to your iPhone, depending on what makes the most sense for your needs.
How to automatically pair a new Apple WatchHow to manually pair Apple WatchHow to pair an existing Apple Watch with a new iPhone (The article continues...)