crear botones de ingresar y registrar usuarios y guardarlos en base de datos

function addUser($username, $password, $email) {
  $password = password_hash($password, PASSWORD_BCRYPT);
  $sql = "INSERT INTO Usuario (username, password, email) VALUES (:username, :password, :email)";
  $statement = $this->pdo->prepare($sql);
  $statement->bindValue(':username', $username);
  $statement->bindValue(':password', $password);
  $statement->bindValue(':email', $email);
  $statement->execute();
}

$user->addUser('user', 'password', 'email@example.com');