// Controller
class ContactUs_Controller extends Page_Controller {

    private static $allowed_actions = array('Form');

    public function Form() {

        // https://docs.silverstripe.org/en/3/developer_guides/forms/how_tos/simple_contact_form/
        $fields = new FieldList(
            new TextField('FirstName', 'Firs tName'),
            new TextField('LastName', 'Last Name'),
            new EmailField('Email', 'Email'),
            new TextareaField('Message', 'Message')
        );
        $actions = new FieldList(
            new FormAction('submit', 'Submit')
        );

        $form = new Form($this, 'Form', $fields, $actions);
        $form->setTemplate('ContactUsFormTemplate');

        return $form;
    }
}