It's just that, on click event you can populate datatable/dataset
and assign it to gridview as datasource. Render the grid using databind event.
You don't need two forms to show gridview and have click event. Both can reside on the same form. Please go through this article. It is little advanced where you can edit the gridview but will give you an idea of how to use gridview on the same page where a button click event happens:
GridView all in one[
^]