Sending data from Arduino to RFID tag and VB.NET application

I want a connection of 4 to 5 push buttons (e.g A,B,C,D), a RFID reader and a few RFID tags. For example when button ‘A’ is pressed, I want to record ‘A’ into a tag that is placed before the reader. The data in the tag is overwritten if the button is pressed multiple times. Besides, I want to keep count of how many times each button has be pressed and send this information to my VB.Net application where it will be used further.
Secondly, is it possible to verify users in a database using RFID reader or Arduino? If yes, what components and approach will I need?

I am a student with no electronic background. My project is a little more complex but this aspect is a major hurdle for me to overcome. Everyone, please help me on this. I would also want to know what electronic components are needed to accomplish this task.

If you feel the information is not sufficient, please let me know. Thank you very much.

You need to decide what sort of RFID reader you will use. It sounds like you need a Mifare classic 1K reader, and a bunch of push buttons.
Readers like this are cheap. Get one that uses an SPI interface rather than serial interface.
Their are plenty of examples on line about reading and writing to them.