Add coloumn to Back office order and customer tables . PS 1.7.7.4

[elly63]

Hello everybody,
first of all I want to thank all the online community and the Prestashop developers who allowed me to have a working shop site without spending unimaginable figures for me.
Now I turn to my question: I use version 1.7.7.4 and I would like to add a column indicating the main customer group in the back office to the "orders" and "customers" pages.
I searched for a while but found nothing within my reach; I chew HTML and CSS (I'm studying PHP and JAVA) and I can easily code files if you tell me where to operate.

Thanks in advance to everyone
PS Sorry for my google english