This sample code came from Bootsnipp. It provides a sample for how to provide an overlay for Bootstrap Carousel slide images:
Bootstrap Carousel with Overlay (Text) http://bootsnipp.com/snippets/6n3Wr
<div class="container">
<!-- Indicators -->
<div id="myCarousel" class="carousel slide" data-ride="carousel">
<!-- Wrapper for slides -->
<div class="carousel-inner" role="listbox">
<div class="item active">
<img src="http://synicsys.com/wp-content/uploads/2014/08/seo-banner-bgd.jpg" alt="Chania">
<div class="carousel-caption">
<h3>Header of Slide 1</h3>
<p>Details of Slide 1. Lorem Ipsum Blah Blah Blah....</p>
</div>
</div>
<div class="item">
<img src="http://allpoints.ph/wp-content/uploads/2013/10/banner.jpg" alt="Chania">
<div class="carousel-caption">
<h3>Header of Slide 2</h3>
<p>Details of Slide 2. Lorem Ipsum Blah Blah Blah....</p>
</div>
</div>
<div class="item">
<img src="http://www.nimble-solution.com/images/slider/banner4.png" alt="Flower">
<div class="carousel-caption">
<h3>Header of Slide3</h3>
<p>Details of Slide 3. Lorem Ipsum Blah Blah Blah....</p>
</div>
</div>
</div>
<!-- Left and right controls -->
<a class="left carousel-control" href="#myCarousel" role="button" data-slide="prev">
<span class="fa fa-angle-left" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="right carousel-control" href="#myCarousel" role="button" data-slide="next">
<span class="fa fa-angle-right" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
<ol class="carousel-indicators">
<li data-target="#myCarousel" data-slide-to="0" class="active"></li>
<li data-target="#myCarousel" data-slide-to="1"></li>
<li data-target="#myCarousel" data-slide-to="2"></li>
</ol>
</div>
</div>
.carousel-control.left
{
background: none;
}
.carousel-control.right
{
background: none;
}
.carousel-control
{
position: absolute;
top: 45%;
bottom: 0;
left: 0;
width: 15%;
font-size: auto;
color: #fff;
text-align: center;
opacity: 1;
text-shadow: none;
}
.carousel-control:hover
{
color: #000;
}
.carousel-indicators
{
bottom: -50px;
}
.carousel-indicators li
{
display: inline-block;
width: 10px;
height: 10px;
margin: 1px;
text-indent: -999px;
cursor: pointer;
background-color: #000\9;
background-color: rgba(0,0,0,0);
border: 1px solid #16a085;
border-radius: 50%;
}
.carousel-indicators .active
{
width: 12px;
height: 12px;
margin: 0;
background-color: #16a085;
}
.carousel-caption
{
position: absolute;
right: 0;
bottom: 0;
left: 0;
z-index: 10;
padding-top: 20px;
padding-bottom: 20px;
color: #fff;
text-align: center;
background: rgba(0,0,0,0.4);
}