I know that when creating the php, if you try to call an index that wasn't defined it will give you the notice from the tile, but I dont know how I can fix it in the way Im trying to create it. Its very basic code. The form:
        <form action="procesar.php" method="get">
            <p>Su nombre: <input type="text" name="nombre"/></p>
            <p>Su e-mail: <input type="text" name="email"/></p>
            <p><input type="submit" name="Enviar"/></p> 
        </form>
And here is the php:
<html>
    <body>
        <p>Hola <?php echo $_POST ["nombre"]; ?><br></p>
        <p>El teu e-mail es: <?php echo $_POST ["email"]; ?></p>
    </body>
</html>
I know there are some missing things in the form like the html or head and body, but Im always getting this :
 
    