Well, first of all you need a section to link to - in your code I can’t see enough content to actually jump to.
Let’s take one of your links as an example:
<a class="nav-link" href="#About us">
Please be aware that you should avoid special characters in your anchors - in your case the space in “#About us”. I would suggest to follow camel case with this: “#AboutUs”, but this depends on how you want to manage naming.
Then you need a section to jump to, for example:
<!--- Your Content --->