First, ensure the devices you're using are connected to the same local network. On a PC, open iTunes or the website of the app you want to stream from. Select the AirPlay symbol in the playback controls and select the TV you want to AirPlay to. If you're using an iPhone, iPad, or iPod touch, open the compatible app you want to use and find the video you want to stream. Then select the AirPlay symbol in the playback controls and select the TV you want to AirPlay to.