How to get a popup box after submitting a form?

[SOLVED] Thanks everyone that replied. I've got a PHP script that is run after a user submited a contact form. This script shows a message in the top left corner saying if it worked properly or if it encountered a problem. Now my question is, how can I put those messages into a popup box? I know there is JS involved, but I barely have knowledge of that. ( Example: http://www.dylanvanheugten.nl/contact.php) PHP ``` $name = $_POST['name']; $email = $_POST['email']; $message = $_POST['message']; $from = 'From: Site Contact'; $to = 'info@dylanvanheugten.nl'; $subject = $_POST['subject']; $human = $_POST['human']; $body = "From: $name\n E-Mail: $email\n Message:\n $message"; if ($_POST['submit']) { if ($name != '' && $email != '' && $subject != '' && $message != '') { if ($human == '12') { if (mail ($to, $subject, $body, $from)) { echo '<p>Uw bericht is verzonden.<br/> U krijgt binnen 3 werkdagen een bericht terug.</p>'; } else { echo '<p>Er is iets mis gegaan tijdens het versturen van uw bericht.<br/> Probeert u alstublieft nogmaals.</p>'; } } else if ($_POST['submit'] && $human != '12') { echo '<p>U heeft de spam preventie som foutief beantwoord.</p>'; } } else { echo '<p>Alstublieft alle velden invullen.</p>'; } } ``` HTML ``` <form method="post" action="contact.php"> <label>Naam</label> <input name="name" placeholder="Naam"> <label>Email</label> <input name="email" type="email" placeholder="Email"> <label>Onderwerp</label> <input name="subject" placeholder="Onderwerp"> <label>Bericht</label> <textarea name="message" placeholder="Laat hier ook uw telefoonnummer achter als u telefonisch contact wilt."></textarea> <label><strong>*Spam preventie*</strong><br/>Wat is 11+1?</label> <input name="human" placeholder="11 + 1 ="> <input id="submit" name="submit" type="submit" value="Verzend"> <label><u>Alle velden zijn verplicht.</u></label> </form> ```