The AirPort Extreme and the AirPort Express are wireless routers from Apple. The AirPort Extreme serves as the primary base station and the AirPort Express can serve as a portable router or wireless extender when paired with an AirPort Extreme base station. These devices can be set up to create a wireless network for Macs and PCs.
Connect to the Internet
Connect your AirPort Extreme to your cable modem or DSL modem using an Ethernet cable and connect its power supply. If an AirPort Express is paired with an AirPort Extreme, it does not need to be connected to an Ethernet cable and can be simply plugged into a power outlet.
Airport Utility
The device is packaged with AirPort Utility software on CD (and most Mac computers have this application pre-installed). Install the application from the CD, if desired, to use the latest version (if you have an older Mac), or if your computer is Windows XP or newer. Turn on your computer’s wireless Airport (or Wifi card) and launch the utility (Macs: in the Utilities sub-folder in the Applications folder; PCs: in the AirPort folder under “Programs” in the Start Menu) to activate the Set Up Assistant.
The application will automatically scan the area for available wireless network devices, specifically for an AirPort base station. Once the AirPort base station is detected, is icon will show up as a device. Select your base station and click the “Continue” button to configure and set up security for your wireless network.
Assign a unique name for your AirPort base station and wireless network, for easy identification and security passwords by typing the information in the fields on the screen. Write down the security information for your AirPort network. Click the “Continue” button to proceed through the assistant. Confirm your country and region, your Internet connection (i.e., DSL or local area network) and type a unique password for your base station on the subsequent screens. Click the “Finish” button to save your basic settings.
Additional Options
The “Manual Setup” function can be selected after the AirPort Utility detects the AirPort base station, or it can be accessed under “Base Station” in the top menu bar. Consider adding a printer to your network or a shared external hard drive by connecting it to your AirPort Extreme with a USB cable. Select these icons at the top of the screen to set up the devices using the assistant.
Consider using the AirPort Express to broadcast iTunes through your stereo (called “AirTunes”). Plug your stereo or speakers into the audio jack on the device and set up your AirPort Express using the AirPort Utility. According to the Apple Website, set up AirTunes by launching iTunes and choosing your stereo or speakers in the pop-up menu located in the lower right corner of the main window.
Article Source: Regina Edwards, eHow Contributor