How to Change Background with Image?

Hello..
I'm so sorry if this question are repost, I need help..

I will change my background with image (repeat) just in PAGE.PHP. I was try to make a code like this at LAYOUT.CSS :
#body1 {
background-image: url("http://mywebsitedotcom/wp-content/uploads/2013/03/bdy-long-tile.jpg");
background-position: 100%;
background-repeat: repeat-x;
}


Then I call the #body1 to my PAGE.PHP...
So I insert body1 like this in my PAGE.PHP :

<?php get_header(); ?>
<div id="body1">
<div id="main" class="row">

<div id="contentpage" class="col8">

<div id="post-<?php the_ID(); ?>" <?php post_class('cf'); ?>>.......

But the result, my background is still white page as before.
Are you can help me to fix it so that it can be as I want?

Thanks...

Best regards...