how to charge my apple watch. I just received it.

You can use any USB-C port on. Personal computer.

You can use the USB-C charger from a recent Macbook Pro, iPhone or iPad.

if you have an older Apple Watch, you can use its charging puck and charger.

read

Charge Apple Watch - Apple Support

if it has an usb-c connector and you do not have anything with that connector you can purchase an usb-c to usb-a adaptor

Amazon.com : usb-a to usb-c adapter