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:
Note: Apple regularly introduces new emojis with new iOS versions. Please make sure you use the latest iOS version to have access to the latest emojis. Instructions for upgrading your phone's software can be found here.
WhatsApp Support Team