How do you facetime each other

The iPad User Guide for iPadOS is good place to start, it being a rich source of information and guidance on the many features and capabilities of your iPad. The User Guide is available as both a downloadable and online version; here are links to both:

https://help.apple.com/epub/ipad/en/

iPad User Guide - Apple Support

Here is another good resource for discovering FaceTime, found using Google...:

Use FaceTime with your iPhone, iPad, or iPod touch - Apple Support

I hope this information and guidance proves to be helpful in leaning about - and resolving any issues with - the FaceTime App.