web.config: <sessionState timeout="60" mode="InProc"/>

login.aspx.cs:Session.Add("userID", dr["id"]);

logout.aspx.cs:

        Session.Abandon();

        Session.RemoveAll();

        Response.Cookies.Clear();

        FormsAuthentication.SignOut();

        Response.Expires = 0;

        Response.Redirect("index.aspx");