Facetime no longer appears as an app icon on the screen of your iPhone or iPad. It is within the contacts app. Go to your contacts and choose a contact that you know has another iOS device. Facetime should show up as an option at the bottom of the contact information page.
Normally, FaceTime is in-built in an iPad mini. However, if your iPad does not have this particular application, you can download it online. You could also take it to any Apple store and have them install it for you.