Adding a link to the footer

Hi @All, i'am new here and i try to add a additional link to the website https://logopaedie-zahn.de Of course i read some (not all) of the posts wich are talking about to change the links or remove them. Please, don't misunderstand my idea! Id don't want to remove your credits like the guy in this post: http://catchthemes.com/support-forum/topic/how-to-replace-the-footer-credits/ ! I would easily add a link for the data, cookie and security guidings at my site and the idea was to add it into the footer, so it could displayed very easy on every page. Maybe you could help me a little bit? Unfortunately i'am not a PHP Developer, so that it is not easy for me to understand all the functions and the places where they would be defined and why. I've created a child theme, and deactivated some search boxes, which i don't need. Kind regards, Axel