You need to create it like this:
<nav>
<ul>
<li><a href="#Home">Home</a></li>
<li><a href="#About">About</a></li>
<li><a href="#Clients">Clients</a></li>
<li><a href="#Contact">Contact Us</a></li>
</ul>
</nav>
And then on the related articles for example:
<div class="article">
<h1 class="title" id="Home">Home</h1>
Sample text
</div>
<div class="article">
<h1 class="title" id="About">About</h1>
Sample text
</div>
<div class="article">
<h1 class="title" id="Clients">Clients</h1>
Sample text
</div>
So what you put after the # in the "href" attribute, refers to the "id" attribute in another html element. (without #)