<html>
<head>
<title>simple form</title>
</head>
<body>
<?php
if (isset($_POST['go'])) { // or $_SERVER['REQUEST_METHOD'] == 'POST'
$firstname = $_REQUEST['firstname'];
$lastname = $_REQUEST['lastname'];
echo "Hello <b>$firstname $lastname</b>";
return;
}
echo ("<h1>A Simple Form</h1>");
echo ("<form action = '".$_SERVER['PHP_SELF']."' method='post'>");
echo ("First name: <input type='text' name='firstname'>");
echo ("<br>");
echo ("Last name: <input type='lastname' name='lastname'>");
echo ("<br><br>");
echo ("<input type='submit' name='go' value='GO!'>");
echo ("</form>");
?>
</body>
</html>