Most credit card readers are serial devices. With a proper driver or serial
interpreter, it is possible to have the data appear as keyboard input.
However, most simply send the data to a serial port, and leave it to the
programmer to receive and interpret the data. Keep in mind that there are
multiple pieces of data (name, card number, expiration date, etc) that are
read from the card. Unless you simply want to dump all of it into a single
text box/field, you will need to parse the data to extract what you need.
Hope that helps.