Tap on the "+" symbol in the top right corner of the  home screen. Then enter the name of the card you would like to add in the search bar and tap on it to select it. The barcode scanner will either open automatically or you will have to tap the orange icon "barcode number" below the card name. After you have scanned the barcode, tap "save" in the top right corner of the screen to save you card.

If the card is not available as a template, you can add it by clicking on "Other card".