You need to download a certain app in app store. You can try this: https://itunes.apple.com/us/app/smileycentral/id416571227?mt=8 and just follow the instructions so you can integrate it to your phone. I actually use another app but i forgot the name. Just search it in app store and it would provide you other emoticon apps.
To get emoji on your iPhone 5 you first have to get an emoji app there's plenty of free ones - then go to settings and find the keyboard settings and choose emoji. There should be instructions in the app. Good Luck!