Navigation question

Hello everybody. Could you please help me?

I am creating a web application with .NET 2008 and c#. I have the following structure directory in my solution:
secure
          training
                    environment
                        Page1.aspx
                        Page2.aspx
                        Page3.aspx
    MasterPage.Master
Default.aspx

Default, Page1, Page2 and Page3 are using the MasterPage and in the MaterPage ...