dynamic background image for template part

thesite.com
I would like to be able to allow the user of this twentytwelve child theme to be upload a featured image to a page (not post) and have that dynamically become the background image (positioned basically the way it is now-see thesite.com)
I think it would need a dynamic url (like wp_get_attachment_thumb_url ), though I’m not using a loop. (was thinking that function has to be used inside a loop.

I am using the code below as a template part. This is what is generating the content on the front page. So basically, I need to get this featured image and use it as a background image for a templage part, and not inside a loop.

<?php $page = get_page_by_title ( 'Welcome' ); ?>

    <div id="welcome-intro" class="clear">

        <?php if ( get_the_post_thumbnail ( $page->ID ) ) : ?>

        	<figure class="entry-page-image">
            	<?php echo get_the_post_thumbnail ( $page->ID, 'full'); ?>
            </figure>

        <?php endif; ?>

        <article id="intro-elements">

            <div class="welcome-entry-content">

            	<?php echo apply_filters( 'the_content', $page->post_content); ?>

            </div>

        </article>

    </div>