How to change Background image

dear Sirs,
I want to put in my background image on the site. I used some free extensions but none of them work well. The problem with them is that every picture hung in the left corner of the site. So when you zoom it stays there. Is it possible to define a background image directly in your template? Also I need to tie the center of the image at the top of the page.

best regards

You can add your background image by adding your definition on bottom of template_css.css (it will override default)

body
{
background-image:url('...your image...');
background-repeat:no-repeat;
background-attachment:fixed;
background-position:center top;
}

Ivane thank you for your help. Failed to add code that you put in the file temlate_css.css.
But when I spotted the mistake and realized that this part should be added to the file template_css.php then everything started OK.

Now part of the code in template_css.php concerning the background looks like this:

body {
font-size:<?php echo $mainFontSize; ?>px;
color:<?php echo $bodyText; ?>;
<?php if ($backgroundImage!="none") { ?>
background:<?php echo $backgroundColor; ?> url(<?php echo $template_path; ?>/images/bg_<?php echo $backgroundImage; ?>.png);
<?php }else{ ?>
background:<?php echo $backgroundColor; ?>;
<?php } ?>
background-image:url(../images/image.jpg);
background-repeat:no-repeat;
background-attachment:fixed;
background-position:center top;
}


In any case, thanks for the great support!