astoller -
Your CSS style looks like this:
.montage {
text-align:right;
}
...which means "apply these styles to any element with the class 'montage'".
However, the only element with that class in your HTML is this:
<div class="montage" />
...which is an empty element, so there's nothing to style. (If you don't know, that trailing slash at the end is the XHTML syntax to close a tag without specifying any content for it.)
You need something like this:
<div class="montage">
<img src="myimage.gif" />
</div>