<!-- BEGIN PHP -->
<?php%20echo%20$_SERVER[%27PHP_SELF%27];?> I get that in the url idk if it helps the rest is the inser.php code.

<?php
$servername = "localhost";
$username = "Placeholder";
$pass = "FakeForShow";
$dbname = "sign up new";


$fullname=$_POST['fullname'];
$username=$_POST['username'];
$email=$_POST['email'];
$password=$_POST['password'];
$codelangs=$_POST['codelangs'];

// Create connection
$conn = new mysqli($servername, $username, $pass, $dbname);
// Check connection
if ($conn->connect_error) {

die("Connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO newusers (fullname, username, password, email, codelang)
VALUES ( '$fullname', '$username', '$email',  '$password', '$codelangs');";

if ($conn->query($sql) === TRUE) {
header("location: index.html");
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}

?>

<!-- END OF PHP -->