Hi,
 
Before you start, make sure your device is on the same Wi-Fi network as your Chromecast.
Open the Google Photos app .
At the top right, tap Cast select your Chromecast.
Open a photo or video on your device to display it on your TV. You can swipe between photos to change what's displayed.

www chromecast setup | www chromecast com | www chromecast com setup

Hi,

Stream as a guest. Step 1: Make sure Wi-Fi is enabled on the guest device (but not connected to your network). Then, attempt to stream by tapping the Chromecast icon at the top of the screen in a Chromecast-friendly app like YouTube, Photos, or Google Play Music. Step 2: A window will appear to connect to a device.

chromecast support | chromecast help | www chromecast setup | www chromecast com