Firefox Login and Password

I set up a form and embbed it at my HTML page allowing users access it through a code, because I want a Login and Password on it.

The problem is: Just Explorer and Safari browsers require login and password but Firefox not. (to the same script)

The Firefox disclose the form view without the code. It not require a login.

I need access code to Firefox too. Do you have any idea about this problem? Do I need any script?

Thanks in advance for a reply.