Adding a background image just below the navigation bar
<p>I want to add a background image (having a full window sized width) just below the navigation bar. It should not cover the whole page length, but starts just below the navigation bar menu, and goes down till a particular specified height. (but the width is full).</p>

<p>I referred to the following but still no results:
<a href="https://stackoverflow.com/questions/11413671/starting-a-background-image-below-navbar-in-twitter-bootstrap">Starting a background image below navbar in Twitter Bootstrap</a>. I am also not using any Bootstrap. </p>

<p>This is what I have coded so far but no results:</p>

<p>HTML:</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;Numberz&lt;/title&gt;
    &lt;link href="https://fonts.googleapis.com/css?family=Open+Sans:400italic,600italic,700italic,400,600,700" rel="stylesheet" type="text/css"&gt;
    &lt;link rel="stylesheet" type="text/css" href="style.css"&gt;
    &lt;meta http-equiv="content-type" content="text/html; charset=utf-8" /&gt;
  &lt;/head&gt;

  &lt;body&gt;
    &lt;nav&gt;

       &lt;img src="image2.png" alt="numberz" width="218px" height="38px" style="margin-left: 100px; margin-top: 15px; float: left; display: inline-block;"&gt;

       &lt;section style="margin-right: 150px;"&gt;
         &lt;ul id="menu"&gt;
            &lt;li&gt;&lt;a href="#"&gt;&lt;b&gt;SIGNUP&lt;/b&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;li&gt;&lt;a href="#"&gt;&lt;b&gt;LOGIN&lt;/b&gt;&lt;/a&gt;&lt;/li&gt;   
            &lt;li&gt;&lt;a href="#"&gt;&lt;b&gt;ACCOUNTANTS&lt;/b&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;li&gt;&lt;a href="#"&gt;&lt;b&gt;BLOG&lt;/b&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;li&gt;&lt;a href="#"&gt;&lt;b&gt;FEATURES&lt;/b&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;li&gt;&lt;a href="#"&gt;&lt;b&gt;PRICING&lt;/b&gt;&lt;/a&gt;&lt;/li&gt;
         &lt;/ul&gt;
       &lt;/section&gt;

    &lt;/nav&gt;

    &lt;div id="backgroundimage"&gt;&lt;/div&gt; //this is the division created for the background image

  &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>CSS:</p>

<pre><code>ul#menu li {
display: inline-block;
float: right;
position: relative;
margin-top: 28px; 
margin-left: 10px;
margin-right: 35px;

}

ul#menu li a {

text-decoration: none;
color: #808080;
font-family: "Helvetica Neue";
font-size: 15px;
}

#backgroundimage {
background: url("image3.png");
width: 1024px;
height: 500px;
background-repeat: no-repeat;
display: block;
position: relative;
background-position: 0 500px;
} 
</code></pre>

<p>Right now It looks like this:</p>

<p><a href="https://i.stack.imgur.com/h6gzf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/h6gzf.png" alt="enter image description here"></a></p>

<p>I want something like this:</p>

<p><a href="https://i.stack.imgur.com/8LzEx.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8LzEx.jpg" alt="enter image description here"></a></p>

<p>Any help would be greatly appreciated.</p>