Calculate when your train is departing, where you have to change train. If you are a tourist and do not have internet abroad, don't worry, you won't need Internet to use Metro Valencia Offline, because is offline!
You can see all the metro stations in the map, click on them, find nearby stations, search by text... Will be very easy to move with the metro in Valencia. And the quick history makes very easy choose the most common routes that you use.
Now, you can check the remaining travels in your metro card. A card can be add typing or scanned by NFC. Then when you calculate a route, the app will show you which cards have enough travels to be used.