how to pass values from one page to other page

Hi
am using 3 layer architecture..
i have a page called x.aspx.cs
in which an passing prjid through query string..
the above wiil be execute when i click a buttn
so i wrote in button click event  like this..
 Response.Redirect("x.aspx?prjId=" + e.CommandArgument.ToString());
now i need to get that prjid in my new page y.aspx.cs(query string)...to which i need to go through x.aspx  page
can some body help me
thank you..
...