Smart Card Reader/Writer

[C# Programming]

Hi dear all,
i have a RFID reader. in my project i have to read data from smart card and also write data in the card.

i attached the reader to com port "com 3".
and i am using ..
private SerialPort comport = new SerialPort();
for the communication.

i am using the object "comport" to read and write data..
the read is..
// Read all the data waiting in the buffer
string data = comport.ReadExisting();
and write is..
// Send the user's text straight out the port
comport.Write(txtSendData.Text);

But i want to read data from a specific block of SMART CARD..
How it is possible...

any one can help me...

thanks!http://www.barakasoft.com/script/Forums/Images/rose.gif