Trouble with Arduino uno v3 + wireless SD shield + xbee pro 51

Hi all,

I'm a newbee on arduino. I receive for christmas a starter kit : nice playground, I love it !!

Now i would like to use a wifi transmission.

I bought arduino wireless shield & the xbee module (51p)

first step, i read this article ""

Toggle the swith on USB
write the first program : and nothing?
Serial.print(Serial.available()) = 0

is there a problem in my wireless shield ?

thanx a lot for your help.