xxxxxxxxxx
$('#myObjectID').css('background-image', 'url(' + imageUrl + ')');
xxxxxxxxxx
jQuery(document).ready(function($) {
$('.bg-image').css("background-image", "url('myurl.jpg')");
});
xxxxxxxxxx
$('myObject').css('background-image', 'url(' + imageUrl + ')');
xxxxxxxxxx
$('myObject').css('background-image', 'url(' + imageUrl + ')');