Assuming you would like a step-by-step guide on how to set up your new Apple Watch:
1. On your iPhone, open the Watch app.
2. Tap the My Watch tab, then tap Start Pairing at the bottom of the screen. Or if you're setting up your first Apple Watch, just tap through the introductory screens until you get to this point.
3. Hold your Apple Watch close to your iPhone. A message should pop up on your iPhone asking if you want to use it to set up your new Apple Watch—tap Continue. If you don't see this message, make sure that Bluetooth is turned on both on your iPhone and watch, then try again.
4. Wait for an animation to appear on your Apple Watch face; when it does, hold the side button down until you see the Power Off slider appear (as shown below), then drag the slider to turn off your watch completely.
5 5. Once your watch is off, press and hold the side button again until you see the Apple logo appear—this means that it's booting back up again (it might take a minute or two).
6 6. Once your watch has restarted, go back to the Watch app on your iPhone and tap Continue on the pairing screen; at this point, you should see a six-digit code appear on both devices (as shown below). Enter this code into your iPhone when prompted and wait for pairing to complete—this might take a minute or two as well depending on how much data needs to be transferred from one device to another .
And that's it! You've now successfully paired an Apple Watch with an iPhone and can begin using all of its features!