Doubt in popup window?

Hi
I am Kumar, I am new user in C-sharpcorner and i am new and beginner  in .net, so i want to learn new thing from us,


I have doubt in popup window. In my application, I have two page (parent.aspx and child .aspx) . Child. Aspx which represent pop up window. In my parent.aspx page I have three button(add,update,delete). When I click add button in the parent page, that will open popwindow (i.e. child.aspx)
 
My requirement is
 
1. when child.aspx (popup window) opens, the user should not allow to access the parent.aspx.. But parent page could view behind the popup window..
2. after we close the child.aspx(popup window), then only user can access the parent page(i.e.parent.aspx)

My Question is

1. How can made this requirement?
2.Which method or any else to use and make this requirement?
3. If anybody answer to this please write the code also because i am new in .net

I hope u all and
Thanks In Advance


Regards by

Kumar Shanmugam