How to create expand/collapse in a gridview?

Hi,

    I am new to this nested gridview .I have to create report for a team. Here i have to create nested gridview with 3 gridview combined together.

In this:

    First Gridview should contain only :

         Location

          +Chennai

          +Pune  

   If i expand the Chennai(location) in this i have to get Second Gridview .

     Second Gridview should contain only:

          Skill

         +higher

         +lower

    If i expand the higher(skill) i have to get the employee status like.

        Grade           Bilable           Non-Billable

         Assistant      5                      4

Please help in this..It ll be helpful for me if you tell solution as soon as possible.....