If you strip the code down to the bare essentials, this is all you need.
Code:
<html>
<head>
<title>Map Demo</title>
<style>
.pin {
position: absolute;
top: 423;
left: 428;
}
</style>
</head>
<body>
<img src="map.gif"/>
<img src="pin.gif" class="pin"/>
</body>
</html>
class="pin" assigns the attributes in the style sheet for .pin to the image.
All you have to do to move the pin around is change top and left attributes in the CSS. The "position: absolute" attribute is necessary to position the pin properly, if you omit it the position attributes are relative to where the image appears on the page rather than the top left corner.
top:0; left:0; is the upper left corner.