why in the heaven no one telling me that I have to put shortcode, and what shortcode is working ... I need to explore deep into /wp-rss-aggregator/includes/shortcodes.php only to finding out what shortcode is used ...
that youtube video is not clear ...
line 32-34
// Register shortcodes
add_shortcode( 'wp_rss_aggregator', 'wprss_shortcode');
add_shortcode( 'wp-rss-aggregator', 'wprss_shortcode');