To do this you need to connect a physical card to your account. Choose which card you want to use (travel card, credit card etc.) and check that it is going to work by swiping it over the QR code on the back of the bike. If the light goes yellow and then red, this means that the bike is capable of reading the card. Then, using the app, rent a freebike. Then Press the menu icon on the map page (to get to the map page press the back arrow < on the scan QR code page). Press the profile icon (1st from top) and then press REGISTER CARD. Your telephone will connect to the bike via Bluetooth and when the connection has been made the back light on the bike will start to flash blue and you will be invited to swipe the card on top of the blue light. A message in the app will tell you when the process has been completed. If your telephone cannot connect to the bike, turn your bluetooth off and then back on again. If you are still not successful, try on another bike.