Need tutorial for a USB RFID kit.

On eBay I got a RFID kit that uses a 125KHz exciter and reads or writes  a card or one of 5 key chin tags. Passive mode.
Here is a photo.


It appeaser to work. It can write to a key chain TAG.
This device could be use to do my Windows password. But not yet, I do not understand how it WORKS and the software has not SOURCE code.

Here is a screenshot from the reader.


What is lacking is documentation. I am very ignorant about this kind of thinmg and I got it to learn more about how it works.

The chip is a type ATA5577 and there is a data sheet, but that does not tell me much.
Does anybody here have experiences with these passive RFID tags?
Where can I find a tutorial?  Hi....RFID (Radio-Frequency Identification) is commonly used nowadays in security systems such as door locks. RFID sets/modules can be very affordable, such as the Mifare MFRC522 chip we will be using in this tutorial.The MFRC522 RFID READERS comes with a RFID’s tag card. The MFRC522 communicates with CARDS or tags up to 1cm using a 13.56MHz electromagnetic field, then sends the data to an Arduino board through SPI communication.You get what you pay for...just sayin...