Well, you can secure a page with .htaccess (search google) like all your PHP pages that are soandso_admin.php, you'd protect with:
<Files *admin.php>
require group admins
</Files>
(you can put a username instead of group like "require user feldon26")
You can look up how to define users and groups on google.com
I don't think you can get the login or password tho. Pretty sure that's between the browser and apache.