Hi
Apple Watch Series 2 can use GPS and a trusted Wi-Fi connection to show you its approximate location. Keep in mind that Apple Watch does not have built-in cellular capability, so it cannot be located when it does not have access to a trusted Wi-Fi network. Location sharing also depends on factors including the watch being turned on and having sufficient battery charge.
In order to set up and use Apple Watch, your loved one will need an iPhone 5 or later, running the latest version of iOS:
Set up your Apple Watch - Apple Support
To be able to track the location of the watch via the Find My iPhone app on your own iPhone, you would then need to add your loved one to your family group via Family Sharing and they would need to agree to share their location with you:
Set up Family Sharing - Apple Support
Once this has been set up, you can (subject to the various limitations) check the location of the watch using the Find My iPhone app on your iPhone or via iCloud.com:
For help with setting everything up, you may wish to contact Apple Support (or make a Genius Bar reservation), taking advantage of the initial 90 days of complimentary technical support that is included with Apple Watch: