How can I connect Apple Watch

To charge your Apple Watch:

1. Handle your Apple Watch and accessories safely and always take off your watchbefore charging it.
2. Plug the Apple Magnetic Charging Cable or Apple Watch Magnetic Charging Dock into a USB power adapter.
3. Plug the adapter into a power outlet. ... 
4. Position the back of your Apple Watch on the charger.

https://support.apple.com/en-us/HT204608