How to center image gallery?

I've used the following code to create an image gallery:http://www.w3schools.com/css/css_image_gallery.asp

It aligns it to the left. I have 9 images in the gallery. What I want to do is have 3 rows by 3 columns of images aligned in the center of the page with margins on both sides but I can't seem to figure it out.

Solution

try this . . you can change the width of the #container

<!DOCTYPE html>
<html>
<head>
<style>
#container{
width: 500px; 
margin: 0 auto;

}
div.img {
    margin: 5px;
    padding: 5px;
    border: 1px solid #0000ff;
    height: auto;
    width: auto;
    float: left;
    text-align: center;
}   

div.img img {
    display: inline;
    margin: 5px;
    border: 1px solid #ffffff;
}

div.img a:hover img {
    border: 1px solid #0000ff;
}

div.desc {
  text-align: center;
  font-weight: normal;
  width: 120px;
  margin: 5px;
}
</style>
</head>
<body>
<div id="container">
<div class="img">
 <a target="_blank" href="klematis_big.htm"><img src="klematis_small.jpg" alt="Klematis" width="110" height="90"></a>
 <div class="desc">Add a description of the image here</div>
</div>
<div class="img">
 <a target="_blank" href="klematis2_big.htm"><img src="klematis2_small.jpg" alt="Klematis" width="110" height="90"></a>
 <div class="desc">Add a description of the image here</div>
</div>
<div class="img">
 <a target="_blank" href="klematis3_big.htm"><img src="klematis3_small.jpg" alt="Klematis" width="110" height="90"></a>
 <div class="desc">Add a description of the image here</div>
</div>
<div class="img">
 <a target="_blank" href="klematis4_big.htm"><img src="klematis4_small.jpg" alt="Klematis" width="110" height="90"></a>
 <div class="desc">Add a description of the image here</div>
</div>
<div>
</body>
</html>