View and preview showing a list of php files

I have installed wordpress 2.8.5 and also can create users through the website. It seems to me that everyone to the website need a login and password. Am I right ?

It is now an intranet website (url = https://10.9.4.138/blog) and I have changed the wordpress folder to blog. After I login as an admin user (url = https://10.9.4.138/blog/wp-login.php), it list out a list of php file just like a ftp server. Shouldn’t it bring me directly to the admin page ? Then, I need to select manually for the index page (url = https://10.9.4.138/blog/wp-admin/index.php). Also, all the view and preview functions are not working as expected. When I view the page, it show me a list of php files. For the preview function in themes, it show me a list of php files, too.