Try to experiment with Inspect Element.
I know that it's empty.
Try making a basic navbar with a ul li or a div thing.
Add this to your index.html
<ul class='navbar'>
<li> <a href="#">Home</a></li>
<li> <a href="#">About</a> </li>
</ul>

and this to your main.css
body {
margin: 0; /* remove the body margin so the navbar could be connected to the top */
font-family: "Helvetica" , "sans-serif"; /* Sets Helvetica sans-serif as the font */
}
.navbar {
background-color: #555; /* set background colour */
margin: 0; /* remove margin here too */
overflow: hidden; /* this kind of makes the navbar work */
}
.navbar li {
float: left; /* Make it go right to left rather than up to down */
list-style-type: none; /* remove dot */
transition: 0.3s background-color; /* add a transition when it's hovered */
}
.navbar li a {
display: block; /* allow padding */
padding: 14px 16px; /* make space inside the links */
color: white; /* font colour */
text-decoration: none; /* remove underline */
}
.navbar li:hover { /* :hover is the style for the object when it's hovered */
background-color: grey; /* Change colour when hovered */
}