Xbee shield discovery

I am trying to communicate with my xbee which is mounted on my arduino through a shield. i have xctu and drivers installed on my mac. But I am unable to discover it on my computer using xctu. How do I proceed? I am trying to start literal communication between my 2 xbees. My computer is not discovering my arduino mounted xbee through xctu. Do I use some code? If yes please refer me the code.

through a shield

Which shield?

Do I use some code?

No. What you need to do is remove the chip from the Arduino before putting the XBee shield on, and then put the chip back (make sure you note which way it goes before you remove it) when done. Or get a better device for connecting the XBee to the PC, like https://www.sparkfun.com/products/9819.