Questions about WordPress.org theme review

To answer your questions:

the wp-config.php is wordpress setting file. how to alter my custom theme?

you don’t need to alter your theme, its simply telling you to turn debug to true within wp-config.php and review your theme, to see if it creating any warnings or errors.
put this line define('WP_DEBUG', true); in your wp-config.php and play around with your site, see if you get any warnings or errors and correct them.

the following is my themes warmHome_setup() function. how to alter it? many thanks.

simply add add_action('after_setup_theme','warmHome_setup'); to your functions.php file

For example:

function warmHome_setup() {
    // all your setup functionality goes here
}
add_action( 'after_setup_theme', 'warmHome_setup');