How do I charge the watch

Apple support have articles online to help guide you:

Check your battery and charge your Apple Watch - Apple Support

If your Apple Watch won't charge or it won't turn on - Apple Support

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More info.

Charge your Apple Watch using the Apple Watch Magnetic Charging Dock - Apple Support

About fast charge on Apple Watch - Apple Support

An  Watch comes with its own charging puck in the box.

Where did you get the watch that you have?

M1 Mac mini, macOS 13; Watch, series 7 GPS/cellular, watchOS 9.1; iPad Pro 2nd Gen, iPadOS 16.1; iPhone 12 Pro, iOS 16.1; TV 4th Gen, tvOS 16.1; HomePods, audioOS 16.1 and Airport Express w/ Airplay 2