Although I can't directly modify the provided code, I do have some advice on how to achieve your desired outcome. First, you should incorporate the background image using CSS. Then, insert the desired div element within the header section following the navigation items. Finally, apply CSS positioning techniques to align it with the background image.
<header>
<nav>
<ul>
<li><a href="Menu.html" style="padding: 0 20px 0 20px;">Menu</a></li>
<li><a href="Burritos.html" style="padding: 0 20px 0 20px;">Burritos</a></li>
<li><a href="index.html"><img class="header-image" src="assets/Headerlogo1.png"></a></li>
<li><a href="Contact.html" style="padding: 0 20px 0 20px;">Contact Us</a></li>
<li><a href="About.html" style="padding: 0 20px 0 20px;">About Us</a></li>
</ul>
</nav>
<div id="wrapper">
</div>
</header>
CSS:
header {
background-image: url(img/your-img.jpg);
background-size: cover;
background-position: center;
height: 100vh; /* or any other preferred value */
background-attachment: fixed;
position: relative;
}
.wrapper {
position: absolute;
width: 1140px; /* adjust based on your requirements */
top: 50%;
left: 50%;
-webkit-transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
transform: translate(-50%, -50%);
}
http://codepen.io/anon/pen/ggQJpX
I hope this guidance helps you achieve what you're aiming for.