How do I add my personal contact information to the locked screen of my iPad 6th generation in case I lose it?

Print your contact information using an app such as Pages, display it, take a screen shot of it, then use it for your lock screen wallpaper.

As an alternate, if your iPad is ever lost, go to https://icloud.com/find and put the iPad into lost mode. One of the lost mode options is to display a message on the iPad’s lock screen.