How can create a popup dialog box above the parent page and both can accessible ?

How can create a popup dialog box above the parent page and both can accessible ?

How can popup a page above the parent page with smaller size ,and need to access both pages simultaneously.
that is  i need to open a popup and select something ,and  that changes affects the parent page immediately and popup is remaining .i need to  touch and swipe the parent page also.


Currently i cannot do that feature.When i click the button  ,a popup box is coming and there is no background page.i need to open popup box above the background page and both must be accessible.

Can you help me?
Thanks