How to prevent Individual aspx files view

Hi ,
Iam new to Asp
I had created an application which has the following pages
1. login page
2. loginfailed Page
3. Home screen
4. Menu
5. Reports
    5a.Report1
    5b.Report2
    5c.Report3

The problem is i can indivijually  view the Pages,
ie.
   1.http://localhost:port/myapplication/Report1
   2.http://localhost:port/myapplication/Menu
Some how i need to prevent this

What kind of design modifications should i do to prevent this ?

Please Help,
Regards


...