I have an article for you that may help you understand Home Sharing a little better:
Home Sharing in iTunes is designed to let you easily share your iTunes media libraries between up to five computers in your household. You can also use Home Sharing to play your iTunes content on your iOS devices and Apple TV (2nd generation) if they are connected to your home Wi-Fi network.
The important thing to note here is that all connected devices must be on the same Wi-Fi network for Home Sharing to be functional. Thanks for coming to the Apple Support Communities!