I copied this gallery code and I need to change there default image to one of mine in my image folder. How can this be done. I code in question is in red.


Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" href="nav_files/css3menu1/style.css" type="text/css" />
<title>Patio's</title>

<style type="text/css">
body {
	background: #00546b;
	margin-top: 20px;
}
h2 {
	color: #eee;
	font-family: Verdana;
}
.gallery {
	width: 816px;
	margin: 0 auto;
	text-align: center;
}
#scroll_box {
	width: 816px;
	margin: 25px 0;
	overflow: auto;
}
.thumbnails {width: 2520px;}
.thumbnails img {
	height: 80px;
	border: 4px solid #000;
	padding: 1px;
	margin: 0 10px 10px 0;
}
.thumbnails img:hover {
	border: 4px solid #00ccff;
	cursor:pointer;
}
.preview img {
	border: 4px solid #000;
	padding: 1px;
	height: 500px;
}
</style>



<script type="text/javascript">
  var GB_ROOT_DIR = "./patio/";
</script>
<script type="text/javascript" src="./patio/ajs.js"></script>
<script type="text/javascript" src="./patio/ajs_fx.js"></script>
<script type="text/javascript" src="./patio/gb_scripts.js"></script>
<script type="text/javascript" src="./patio/iwebalbumpics.js"></script>
<link href="./patio/gb_styles.css" rel="stylesheet" type="text/css" />
<link href="./patio/style.css" rel="stylesheet" type="text/css" />
</head>
<body>

<table width="770" border="0" align="center" cellpadding="4" cellspacing="4">
  <tr>
    <td width="750"><img src="images/new banner.gif" width="755" height="173" alt="banner" /></td>
  </tr>
  <tr>
    <td><div align="center"><center><ul id="css3menu1" class="topmenu">
	<li class="topfirst"><a href="index.html" title="Home" style="width:51px;height:16px;line-height:16px;">Home</a></li>
	<li class="topmenu"><a style="width:159px;height:16px;line-height:16px;"><span>Interlocking stone </span></a>
	<ul>
		<li class="subfirst"><a href="retaining_walls.html" title="Retaining Walls">Retaining Walls</a></li>
		<li><a href="sidewalks.html" title="Sidewalks">Sidewalks</a></li>
		<li><a href="drive_ways.html" title="Driveways">Driveways</a></li>
        <li><a href="patio.html" title="Patio's">Patio's</a></li>
 
	</ul>
	</li>
	<li class="topmenu"><a  style="width:114px;height:16px;line-height:16px;"><span>Landscaping</span></a>
	<ul>
		<li class="subfirst"><a href="boulders.html" title="Boulders">Boulders</a></li>
		<li><a href="yard_leveling.html" title="Yard Levelling">Yard Levelling</a></li>
		<li><a href="hauling.html" title="Hauling">Hauling</a></li>
        <li><a href="window_wells.html" title="Window Well & Foundation Dig">Window Well & Foundation Dig</a></li>
        
        
        
	</ul>
	</li>
	<li class="topmenu"><a  style="width:89px;height:16px;line-height:16px;"><span>Demoliton</span></a>
	<ul>
		
         <li class="subfirst"><a href="step_demo.html" title="Step demo">Step Demo</a></li>
        <li><a href="commercial.html" title="Commercial Concrete Floors & excavation">Commercial Concrete Floors & excavation</a></li>
        <li><a href="driveway_demo.html" title="Driveway Demo">Driveway Demo</a></li>
        <li><a href="garage.html" title="Garages">Garages</a></li>
        <li><a href="interiorgutouts.html" title="Interior Gutouts">Interior Gutouts</a></li>
        <li><a href="specialty.html" title="Specialty">Specialty</a></li>
        
        
	</ul>
	</li>
	<li class="topfirst"><a href="testimonials.html" title="Testimonials" style="width:114px;height:16px;line-height:16px;">Testimonials</a></li>
    <li class="topmenu"><a  style="width:96px;height:16px;line-height:16px;"><span>Contact us</span></a>
	<ul>
		
         <li class="subfirst"><a href="contactus.html" title="">Contact</a></li>
        <li><a href="about.html" title="About us">About us</a></li>
    
    
        
	</ul>
	</li>
    
</ul></center>
</div></td>
  </tr>
  
 
</table>

<div class="gallery">
        <h3>Patio</h3>
            <div id="scroll_box">
                <div class="thumbnails"> 
<img onmouseover="preview.src=img1.src" id="img1"img src="patio1/patio1.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img2.src" id="img2"img src="patio1/patio2.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img3.src" id="img3"img src="patio1/patio3.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img4.src" id="img4"img src="patio1/patio4.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img5.src" id="img5"img src="patio1/patio5.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img6.src" id="img6"img src="patio1/patio6.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img7.src" id="img7"img src="patio1/patio7.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img8.src" id="img8"img src="patio1/patio8.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img9.src" id="img9"img src="patio1/patio9.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img10.src" id="img10"img src="patio1/patio10.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img11.src" id="img11"img src="patio1/patio11.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img12.src" id="img12"img src="patio1/patio12.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img13.src" id="img13"img src="patio1/patio13.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img14.src" id="img14"img src="patio1/patio14.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img15.src" id="img15"img src="patio1/patio15.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img16.src" id="img16"img src="patio1/patio16.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img17.src" id="img17"img src="patio1/patio17.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img18.src" id="img18"img src="patio1/patio18.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img19.src" id="img19"img src="patio1/patio19.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img20.src" id="img20"img src="patio1/patio20.jpg" alt="Image Not Loaded"/>
<img onmouseover="preview.src=img21.src" id="img21"img src="patio1/patio21.jpg" alt="Image Not Loaded"/>
                <!--end .thumbnails--></div>
            <!--end scroll_box--></div>
        <div class="preview"> <img id="preview" src="http://bit.ly/2rz3hy" alt="No Image Loaded"/> </div>
    <!--end gallery--></div>

<div>
<center>
<p>Copyright 2011 REN Hauling</p>
                  <h4>Website designed by <a href="http://www.cjwebconsulting.com" target="_blank">CJ Web Consulting</a>              </h4>
              </center></div> 

</body>
</html>