Each .nav-link should have text that corresponds to the header text of its related section (e.g. if you have a “Hello world” section/header, your #navbar should have a .nav-link which has the text “Hello world”).
To display your code in here you need to wrap it in triple back ticks. On a line by itself type three back ticks. Then on the first line below the three back ticks paste in your code. Then below your code on a new line type three more back ticks. The back tick on my keyboard is in the upper left just above the Tab key and below the Esc key.