Sharepoint Team Services (Access & Permission)

[Johnny]

The Web access, how can limit a group of people to access the share Point
services.
It seems to me everyone can go to that website, click on Site Settings and
change the items.
I have setup the users with the permission to Browse, Author, Contributor.
Why is not working. I don't see the user logon windows. How can I enable
that ?

When go to https://servername/ProjectServer, it will prompt me Windows
Username and Password and then the Project Server logon page.

How can I make the SharePoint Team Services works like that ?

Johnny