Replace div's content after submission
<p>I went through several posts but I am not able to find an answer for what I'm trying to do. If I missed something pls point me to the post.</p>

<p>I have a form that appears in small box. What I want to happen is to instead of redirecting the visitor to a different page in order to see the 'Thank you' message to keep him to the same page and change the content of the div.</p>

<p>I have managed to go half way there (thanks to a post found here).</p>

<p>I am able to not redirect the visitor plus show him a 'Thank You' message, but I am not able to refresh the content. I still see the form.</p>

<p>I'm only familiar with html, css and a bit php so if there's a solution that doesn't include jquery, etc. would be great.</p>

<p>Here's what I have so far:</p>

<p>HTML</p>

<pre><code>&lt;div id="mc_embed_signup"&gt;  
                    &lt;form action="" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" novalidate&gt;
                    &lt;div class="mc-field-group"&gt;
                    &lt;input id="firstname3" type="text" value="" name="FNAME" placeholder="'Ονομα"&gt;
                    &lt;/div&gt;

                    &lt;div class="mc-field-group"&gt;
                    &lt;input id="primaryemail3" type="email" value="" name="EMAIL" placeholder="Email"&gt;
                    &lt;/div&gt;

                    &lt;div id="mce-responses" class="clear"&gt;
                    &lt;div class="response" id="mce-error-response" style="display:none"&gt;&lt;/div&gt;
                    &lt;div class="response" id="mce-success-response" style="display:none"&gt;&lt;/div&gt;
                    &lt;/div&gt; 

                    &lt;div class="myResultDiv"&gt;

                    &lt;input name="subscribe" class="button_link hover_fade large_button red button_widget" type="submit" value="ΣΤΕΙΛΤΕ ΤΟ ΔΩΡΟ ΜΟΥ!"&gt;&lt;/div&gt;
                    &lt;/form&gt;

                    &lt;?php if (isset($_POST['subscribe'])) : ?&gt;
                    &lt;p&gt;Thank you for subscribing!&lt;/p&gt;
                    &lt;?php endif; ?&gt;

                    &lt;/div&gt;

                    &lt;div&gt;
                    &lt;p class="under_button2"&gt;&lt;/p&gt;

                    &lt;div class="af-clear"&gt;
                    &lt;/div&gt;

                    &lt;/div&gt;
                    &lt;/div&gt;                  
                    &lt;!--End mc_embed_signup--&gt;      
</code></pre>
