How do I put icloud calendar in thunderbird editable?

Someone?

I managed to enter the calendar (after putting it public) using the antenna symbol, copied link, posted it in cadav and it came up!!! Halleluha!

But, now I cannot edit from thunderbird. Getting a yellow triangle with exclamation if I am putting an event from thunderbird...

Anybody out there who can help?

Regards, Anette.