shortcodes is a cool feature to a WordPress site. You can do much stuff using the shortcodes. Galleries, videos, and various other functionality would require a lot of code editing. By using shortcodes the HTML and other markups are added dynamically directly into the post or page where the user wants them to appear.
Following is the basic example which you help you to understand the shortcode
<?php
add_shortcode('image_emb', 'image_emb');
function image_emb($atts){
$atts = shortcode_atts(array(
'src'=>'',
'height'=>'388',
'width'=>'600',
'title'=>''
), $atts);
echo '<img width="' . $atts['width'] . '" height="' . $atts['height'] . '" src="' . $atts['src'] . '" />';
}
?>[image_emb src="yourpath/abc.jpg"]
Now implement same code as shown above step and check your output on the browser.