Just enable it using the app "Quick Voice" or by Settings->Language->Keyboard. Then select the Voice keyboard by swiping your keyboard. If you can't find "QuickVoice" in keyboard selection under Settings->Language->Keyboard, reboot and retry. Once you get a keyboard with 4 buttons, like the one in screenshots, hold down the mic button and talk clearly and loudly, once done just release the mic button, you'll see a rotating gear that means "please wait...".