1/ select the camera app
2/ select the setting icon-- the cog wheel-
3/scroll down the menu that comes up, and select voice control to turn on or off.
4/ When on, you should see on the screen the message "You can take pictures with voice commands like Smile, Cheese, Capture, and Shoot."
Anyone of these works--(you may find that the voice recognition picks up better on one versus another)
I have this set up on my tab 3 and sometimes it takes pictures by itself when no words that it should recognise have been spoken. Also some words that it SHOULD recognise dont always work. It is fun to use though and it is a talking point so I love it.