twitter bootstrap background images for two sections - html

Question

I am using Twitter bootstrap and I have a one page website with a top section and a bottom section. I would like to place different background images in each section; however, I cannot seem to get it to work- are there any suggestions?
Here is my HTML:
<section class="container-fluid">
<div class="row-fluid">
<div class="span4 offset4">
<br />
<img src="images/logo.png" width="400" height="400" image alt="image" />
</div>
</div>
<div class="row12">
<h3><p class="text-center"></p></h3>
<h4><p class="text-center"></p></h4>
<h4><p class="text-center"></p></h4>
<br />
<br />
</div>
<div class="row-fluid">
<ul class="thumbnails">
<li class="span1 offset4">
<a href="#" class="thumbnail">
<img src="images/MAIL_icon.png" width="50" height="50" image alt="image" />
</a>
</li>
<li class="span1">
<a href="#" class="thumbnail">
<img src="images/DRIBBBLE_icon.png" width="50" height="50" image alt="image" />
</a>
</li>
<li class="span1">
<a href="#" class="thumbnail">
<img src="images/TWITTER_icon.png" width="50" height="50" image alt="image" />
</a>
</li>
<li class="span1">
<a href="#" class="thumbnail">
<img src="images/INSTAGRAM_icon.png" width="50" height="50" image alt="image" />
</a>
</li>
</ul>
</div>
</section>
and my CSS:
#top_section {background-image: url(images/urban_lights.png);
}

Answer 1

Assign different background to your different section.
#topSection {
background-image: url("url/to/image.jpg");
}
#bottomSection {
background-image: url("url/to/image.jpg");
}

Answer 2

If your CSS and images are in separate folders found in the root directory try:
#top_section {background-image: url(../images/urban_lights.png);