Guys, if you don't know the answer, don't have any idea how the software in question works, the most helpful thing is to refrain from answering and suggesting that someone moves to an entirely new music service when the one he is already invested in provides multiple ways to do exactly what he's asking.
Home Share is the free way to do this, but you have to be on the same network as the computer hosting the iTunes library (which of course must also be powered on).
iTunes Match is the paid method, but it will give you direct streaming access to your entire library from any device from any network.