Hi Satu,

No such thing as a stupid question. You are correct, the only place to see the field is on the individual customer page. If you want it to show up on the main customer list, you would need to make a new column for that. I suggest opening customers.php file and search for extrafield. From there, you can figure what needs to be copied to your new column.

The radio button code looks ok at first glance. Did you upload it to your server and see if it works?