header Image not displaying

I am having difficulties with header image not showing up at all with themes that I have downloaded over the internet. I am really new to WP. I have downloaded it yesterday. Am I missing something? I also don’t know much about writing code.

Below is code from one of the themes.

/*	To accomodate differing install paths of WordPress, images are referred only here,
	and not in the wp-layout.css file. If you prefer to use only CSS for colors and what
	not, then go right ahead and delete the following lines, and the image files. */

<?php /* Checks to see whether it needs a sidebar or not */ // if ((! $withcomments) && (! is_single())) { ?>
	#page { background: url("<?php bloginfo('stylesheet_directory'); ?>/images/buildingdreamsbg.jpg") repeat-y top; border: none; }
<?php // } else { // No sidebar ?>
	/* #page { background: url("<?php bloginfo('stylesheet_directory'); ?>/images/buildingdreamsbgwide.jpg") repeat-y top; border: none; } */
<?php // } ?>
	#header { background: url("<?php bloginfo('stylesheet_directory'); ?>/images/buildingdreamsheader.jpg") no-repeat bottom center; }