Thanking Gransnet for a freebie !

Hi All, I have just received a lovely book for my Grandchildren in a free draw from Gransnet.
I am an active user/reviewer on the book club pages and on there you can say 'Thank You' for receiving a book, but I could find nowhere that I could say thanks for the Freebie.
Anyway, I'm doing it here and hope that it gets to the right people.The book is called 'When Dad showed me the universe'.