Ok this
<form action="mailto=suggestion@grabugegraphique.org" method="post">
isn't valid.
You need to send the form output to a script to be processed, that could be the same page or another page. I'll assume another page called feedback.php, that would mean changing the line to
<form action="feedback.php" method="post">
Then your feedback.php would be like this
<?php
addslashes(htmlspecialchars(trim(extract($_POST))));
$message = "nomecole: ".$nomecole;
$message .= "ville: ".$ville;
$message .= "textinput32: ".$textinput32;
$message .="cycledenseignement: " .$cycledenseignement ;
$message .="nombredeleves: " .$nombredeleves;
$message .= "fonctionecole: ".$fonctionecole;
$message .="fonctionniveau: " .$fonctionniveau;
$message .="\ntextareainput: " .$textareainput;
mail("suggestion@grabugegraphique.org", "Questionaire Results", $message);
echo"Thanks for your input."
?>
This would send you an email with the values entered in the form.