Add Custom Background

functions.php

$defaults = array(
'default-color' => '',
'default-image' => '',
'default-repeat' => '',
'default-position-x' => '',
'default-position-y' => '',
'default-size' => '',
'default-attachment' => '',
'wp-head-callback' => '_custom_background_cb',
'admin-head-callback' => '',
'admin-preview-callback' => ''
);
add_theme_support( 'custom-background', $defaults );