Centering embeded slideshow

Hello everyone. This is my first post. I am trying to center an embedded slideshow on the page, so it matches the header image as far as centering. I am not sure how to do this.

Here is a link to the page. I’m trying to center the part that says “Gallery Index” with the header.

http://www.perr.com/wp-gallery/gallery/

Here is the code that embeds it.

<iframe src=”http://www.perr.com/gallery/&#8221; height=”870″ width=”790″></iframe>

I am using the Twenty Ten theme. Any help would be appreciated – Bruce