Fontawesome/ Alternative text are not working

Hi, I am using the demo of “Grocery”. We were trying to change the icon from the header builder. There is a section of text/html on the top bar. First, we were trying to use the Alternative Text, but we don’t know the code for this, please kindly help.

And the second we were trying to use Fontawesome, we put the code but the icon is also not showing correctly.

Thanks in advanced