Do you mean you want to get the group permissions on a specified file, and then set the permissions on all other files (recursively) to that value? What have you tried so far?
Owner permissions can be useful:
Is there a reason why 'owner' permissions exist?
Out of the two options to change permissions:
chmod 777 file.txt
chmod a+rwx file.txt
I am writing a document to send out to our customers, detailing that they need to change the file permissions of a certain file.