Download and add to your theme:
http://malsup.github.com/jquery.form.js

Add to your Functions PHP:

wp_enqueue_script("jquery");
wp_enqueue_script( 'jquery-form-js', get_template_directory_uri() . '/js/jquery.form.js', array('jquery'), '3.51.0-2014.06.20', true );

In any SINGLE CRED form JS Editor:

jQuery(document).ready(function() { 
            
            jQuery('#cred_form_4988_1').ajaxForm(function() { 
                alert("Thank you for your comment!"); 
            }); 
        }); 

Replace #cred_form_4988_1 with the actual ID of the CRED Form you’ll see in your browser console asa in this:

<form enctype="multipart/form-data" id="cred_form_4988_1" class="cred-form cred-keep-original" action="/toolset/2015/07/08/ajax-edit/?cred-edit-form=4988&amp;_tt=1436396327" method="post">

If you have MULTIPLE CRED FORMS (of same form), outputted in a Views Loop
Means, you got x posts, and therefore x CRED Forms of same type,the ID of CRED is continuously increased by one, so the a above jQuery breaks. You should use here:

jQuery(document).ready(function() { 
jQuery("[id^=cred_form_1096]").ajaxForm(function() { 
    alert("Thank you for your comment!"); 
}); 
}); 

We use now ("[id^=PART_OF_ID]")

You can also seek for all elements which contain (*=) or end up with ($=) known part of ID/class/type.
(example, id^, id*, id$)

DOC Links:
http://malsup.com/jquery/form/#getting-started