How to stream music from iTunes on your Mac or PC or from your iPhone, iPad or iPod touch (iOS 5.1 or later) to your stereo or speakers using AirPort Express as a standalone Wi-Fi base station or as one of several Wi-Fi base stations.
Once the AirPort Utility is installed launch the program.
When it starts you'll see the new base station listed on the left. Make sure it is highlighted. Click Continue.
In the fields presented in the window give the AirPort Express a name (for instance it it's located in your home office maybe call it "office" or "bedroom" if that's where it is) and a password that you'll remember so you can access it later.
1. You'll be asked whether you're connecting the AirPort Express to an existing network (choose this if you already have a Wi-Fi network) replacing another (if you're getting rid of your old network hardware) or connecting via Ethernet.
2. For the purposes of this tutorial I'm going to assume that you've already got a wireless network and that this is just an addition to it. Choose that option and click Continue.
3. You'll see a list of the available wireless networks in your area. Select yours to add the AirPort Express to. Click Continue.
4. When the changed settings are saved the AirPort Express will restart.
5. When it restarts the AirPort Express will appear in the AirPort Utility window with the new name you gave it and will be ready to use.
1. Connect your DSL or cable modem to your AirPort Express using the WAN Ethernet port.
2. Connect your AirPort Express to your home stereo or powered speakers.
3. Plug AirPort Express into the power outlet. There is no "on" switch.
4. Use AirPort Utility to create a new network. Ensure that "Enable AirPlay/AirTunes" is checked in the Music tab.
5. Open iTunes on your computer and choose the AirPort Express(es) you wish to stream music through from the speakers pop-up menu in the lower right-hand corner of the iTunes window.
How To Setup Airport Express on MAC?