At this time, we do not have emoticons built into WhatsApp for iPhone. However, emoticon support is built into the iPhone by using the Emoji keyboard. Go to iPhone Settings > General > Keyboard > Keyboards > Add New Keyboard then select Emoji.
Once the Emoji keyboard is enabled you can access it here:
Please note that iOS 6 has introduced additional emoji characters. In order to send and receive all of the new emoji characters, you will need to have upgraded your iPhone's software to iOS 6 or later. Instructions for upgrading your phone's software can be found here. iOS 8 introduced even more emoji characters that will not be available on older operating systems.
WhatsApp Support Team