passing User control Gridview popup to parent page

I have this User  Control which contains

Gridview -  container from what I pass from the parent page Done
TextBox - search item/date from the Gridview Done
  inside a modal popup
What I want to know/understand is how can I pass the selected Item from GridView Back to the Parent page which other page can benefits or
How can the parent page gets Gridview selected value.

Note:
This controls well be user for about 10 pages.