Use AirPlay to display video from your Mac on an HDTV - Apple Support
"AirPlay-enabled speaker system: Most dedicated AirPlay speakers are easy to set up. Often, you just connect an iOS device to the speaker via a USB cable, and then use a dedicated iOS app to configure the speaker to join your local network. Other models create their own Wi-Fi network; you join that network on your iOS device or computer, connect to a built-in Web server on the speaker, and then reconfigure the speaker to join your network. In either case, the speaker will come with a setup guide for performing this procedure. (During this process, you can also—and probably should—give the speaker a useful name, such as Kitchen Speaker; this name is how you’ll identify the speaker when using other devices on the network.) "
"AirPort Express Configuring an AirPort Express as an AirPlay receiver is a bit more involved, but it’s still fairly easy. If the Express is already a part of your network, you launch AirPort Utility, select the Express, and click Edit. Next, click the AirPlay tab, check the Enable AirPlay box, give the Express a useful name, and then click Update. "
ref: http://www.macworld.com/article/2039770/how-to-get-started-with-airplay.html