Securing web site

Hi, i'm building a website which will be used in local area network using windows authentication.
There will be about 70 users.
I have pages like (dropdown menu)
Page1list.aspx           Page2list.aspx  ....
Page1edit.aspx          Page2edit.aspx  ....
Page1insert.aspx        Page2insert.aspx  ....
The database is SQL Server 2008 Express. What i want to do is ;
all of the users will see and open page1list.aspx, page2list.aspx ..... and the other pages will be seen but can not be opened by
all users, only five of the users will be able to edit or insert into the databse.
Can any one advise me a starting point.
Thanks.
 
...