How does Airport work, what do I need?

Do you already have a Wi-Fi network set up? If so, then what does it consist of?

It may be possible to extend the range of your existing router by using an Access Point like an Airport Express. However, they are designed to work best only with Apple routers. They can only be connected to your existing router in bridge mode (Join existing network,) if they will work at all.

For better compatibility you might consider getting a similar device made by the same company who made your router.

I used an Airport Express to extend my 8-2.11n Netgear router. It worked fine, BUT the signal strength improved and my performance almost tripled when I replaced the Netgear with an Apple Extreme a couple of months later. The new Apple 802.11n wireless devices use multiple frequencies to improve throughput (and decrease interference).

The Extreme can act as a router. The Express is just a single point wireless access point.

No. The Apple router is the Airport Extreme Base Station or the Apple Time Capsule. However, an Airport Express is capable of acting as a wireless router or extending an AEBS' or Time Capsule's range.

To extend the range of a router, you would locate the AEX where you need to get a stronger signal, then join the existing wireless network created by your router. You can also connect the AEX with an Ethernet cable if you have the ability to run one from where the AEX would be located.

In any event the AEX would have to be located a remote distance from your router in order to extend the router's range. For a wireless connection that would be not more than 150 feet in clear space. In a house it would have to be much closer due to signal attenuation caused by walls, ceiling, floors, and windows.

An AEX can be used as a router. It is capable of making a wireless network.