Desarrollar software

I need to create a membership managment software for a gym. What when you register a member the program itself creates a BARCODE (in order to print it on a card) for this client. Then when the client enter the gym (in order to do that she/he will need to pass the card into a barcode scanner) so when that happens, if the client didn't pay the month the program should tell me with an alarm or something like that. Will give more information later!