Q: AirPlay icon in itunes lower right???

First of all this is showing up under the community heading "using and iphone' but apple doesn't list the opton of using macbook which is what I'm using.  Why the..  not?  I am having trouble setting up an Apple Express and finding AirPlay on my iTunes window.  This Apple Express was sold to me as fuctioning with a Macbook pro.  Why no link to that community?  Can anyone here possibly help me get going?  

I've reset the router but still don't see the AirPlay icon in the lower right corner of the iTunes window.  I set up the Apple Express under the name of my home network, and my home network is avialable and at full power in the wifi network drop down at the top of my finder window.  My Ariport exress is on, and supposedly is set up correctly.  But maybe I should had set up AE under it's own name that way I could actually see it in the wifi drop down.  (Not sure how to redo that, but should that matter? Green light is on so it's connected to my home network.

Thanks