How to pur smiley faces in my messages on Iphone 5?

I installed Emoji, but it doesn't show up when I go to messages.

On the keyboard, you tap the icon to the left of the spacebar which looks like a minimalistic globe. There you'll have access to dozens of emoji. If that doesn't work go to Settings > General > Keyboard > Keyboards and add the Emoji keyboard. After you've done that, it will show up when you tap to previously described globe icon next to the spacebar.

Done!