Like tagging friends on Facebook, you can also Mention friends on photo updates you release in Moments.

1. Go to Discover > Moments and tap once on the Camera icon at the top right.
2. Select Take Photo if you want to snap a new picture or Choose Photo if you want to share the photo that is already in your device.
3. In the status page, tap on Mention and tick friends you want to tag. Tap on Send to update your Moments.

_{credit : hongkiat.com}