modify footpage in personnalisation / theme option / footpage option edito

Hello I try to modify this footpage including a link to legal mentions , but I don't manage to do it. Its written that we can add html code in that section or shortcodes or text I tried © [the-year] [site-link] the shortcodes provided in example work perfectly but the html link to my legal mentions doesn't work does a shortcut to a intern page exist in that theme? It s written that : " You can add custom shortcodes, which will be automatically inserted into your theme. Some shorcodes: [the-year] and [site-link] for current year and site link respectively. " but where can I find the other shortcodes? or do I have to create it myself? Thanks for helping me I am a novice. Fred