Players unlock the friend feature at level 15. 

Adding Friends
There are two ways to add a friend, from within the chat or from your profile page. 

Within Chat
To add a friend from within the chat feature, click the icon in the upper right corner. From there, a menu will appear, and you will be able to select how you want to add your friend.

Profile Page
To add a friend from your profile page, scroll to the bottom and click the "add friends" button. From there, a menu will appear, and you will be able to select how you want to add your friend! 

Different Ways to Add Friends
When selecting the "Add Friend" icons on either your profile or chat, you will get a menu that looks like this:

Where you can add a friend through your preferred method!