In order to read the QR Codes on the shirts, you need a smartphone with a QR Reader app. There are many QR Readers for iPhone, Android, and Blackberry. Greatest of all, they are all free. For iPhone I would recommend QR Reader
, for Android I recommend Barcode Scanner
, and I don't have a Blackberry to test this on, however this app
seems pretty solid. Feel free to recommend a QR reader you have had better experience with. Once you have downloaded the app, you can test it out on this.