There are two types of icons:

 

- Icons in file “index.html”

From THIS LINK you can choose icon. Click it and copy the code. After that you can place Font Awesome icons just about anywhere with the <i> tag or you can replace an existing icon.  

Example: <i class="fa fa-check" aria-hidden="true"></i>


- Icons in file “entrostyleXX.css” 

From THIS LINK you can choose icon and copy the corresponding code. After that you can replace the code in style.css.

Example: In ‘entrostyle1’ at the hover of a button, appears icon, which is loaded by css file (row 289)

body .pricing-table-l1 .pricing-table-plan .pricing-table_cta .cta-btn .icon-arrow:before {

  content: "\f061";

….

}

                You need to change only the value in brackets - \f061


*XX is the number of style wich you want to use