Forwarding data to another aspx page

Question

Hello

I already have an aspx page where, lets say has a dataGrid with a list of movies (movie names as links), when the user clicks on a particular movie, I get the value of the pressed item from the dataGrid, but what I want is when the user clicks, a new page opens, lets say done.aspx using: Response.Redirect("done.aspx?user_id="+value)

But when creating the done.aspx page, how do I make it expect a parameter?

When I come to compile the aspx page, it doesn't recognize the parameter that was passed. Seems I need to define it somewhere