i already attach picture of connection of rfid to arduino.
No you didn't.
But thanks for doing so now. It looks like that is wired up correctly?
i dont know how to troubleshoot.
So you look with an oscilloscope at the yellow or blue line and see if you can detect any activity.
If you can measure the signal and try and determine the baud rate. Then set the same baud rate in your sketch.
Then look at the R out signal into the Arduino, is this the right way up for TTL serial data. That is when there is no activity the line sits high? If not then swap over the yellow and blue wires.
You still need a proper data sheet, those you have posted already are not good enough.