Here is the guide that can help you with Icons in Carena theme.You can use icons from this page https://fontawesome.com/cheatsheet , most of them will work with theme. Just use them with fa extension. For example, if you want to use the first icon on the page address-book , the code will be
<i class=“fa fa-address-book”></i>
If you want to go further and want to add your own set of icons in KC default Icon selector, here is the process to do it.
First please go here https://icomoon.io/app/ and create set of icons you want to use.
After selection, download those fonts from bottom tabs. When you open the downloaded zip, you will find style.css file inside it.
Now you can plug these icons in KC by following KC’s own guide https://docs.kingcomposer.com/import-icons
Its recommended that you add code given in above link in Carena-child theme’s functions.php file. So that you can safely update main Carena theme in future.