How to use other Icons in Labels?

How to use other Icons in Labels?

Hello
I recently learned to use icons in my Labels, but a few days ago I found myself in the situation that the icon I wanted to use was not in the palette of default Icons that are displayed.
I also saw the link that allows you to search for other icons in Fontawesome, where I found the icon I want but I don't know what I should configure to be able to use it in my Label.
Could you help me solve my problem?