Hi ,wooinvi - 

It looks like you were trying to pair your Apple Watch manually to your iPhone.  What happens when you try to pair it automatically?

Set up your Apple Watch - Apple Support
https://support.apple.com/en-us/HT204505​

Set up your Apple Watch

To get started with your Apple Watch, pair and sync it with your iPhone.

     

Before you begin

• To use your Apple Watch, you'll need to pair it with an iPhone 5 or later running iOS 8.2 or later. You can pair one Apple Watch to your iPhone at a time.
• On your iPhone, go to Settings > Bluetooth and make sure Bluetooth is on.
• Make sure your iPhone is connected to Wi-Fi or a cellular network.
• Turn on your Apple Watch by pressing and holding the side button next to the Digital Crown until you see the Apple logo.
• Make sure both devices are charged, and keep them close together as you pair and sync them.

Open the Apple Watch app on your iPhone.

Then tap a language on your Apple Watch. You can scroll through the list by rotating the Digital Crown or swiping the screen.
 

Pair your devices.

Tap Start Pairing on your Apple Watch and again on your iPhone. A pairing animation should appear on your Apple Watch.
 

Hold your iPhone over the pairing animation on your Apple Watch.

Center the watch face in the onscreen viewfinder on your iPhone until a message says Your Apple Watch is Paired.


 

Regards,