Transfer selected rows from one gridview to another in next page on btnclick evnet

<form id="form1" runat="server">

       <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" Height="310px" Style="margin-right: 56px" Width="704px">
           <Columns>
               <asp:TemplateField HeaderText="Select">
                   <ItemTemplate>
                       <asp:CheckBox ID="cbSelect"
                           CssClass="gridCB" runat="server"></asp:CheckBox>

                   </ItemTemplate>
               </asp:TemplateField>

               <asp:BoundField DataField="Title" HeaderText="Title" />
               <asp:BoundField DataField="Date" HeaderText="Date" />
               <asp:BoundField DataField="events" HeaderText="events" />
           </Columns>
       </asp:GridView>
       <asp:Button ID="btnCopy" runat="server" Text="Copy Rows" OnClick="btnCopy_Click" />

   </form>

public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                SPWeb web = SPContext.Current.Web;
                SPList list = web.Lists["Calender event selection list"];
                SPListItemCollection items = list.Items;
                GridView1.DataSource = items.GetDataTable();
                GridView1.DataBind();
            }
        }

      

        protected void btnCopy_Click(object sender, EventArgs e)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("Title");
            dt.Columns.Add("Date");
            dt.Columns.Add("events");

            foreach (GridViewRow row in GridView1.Rows)
                if (((CheckBox)row.Cells[0].FindControl("cbSelect")).Checked)
                    dt.Rows.Add(row.Cells[1].Text, row.Cells[2].Text, row.Cells[3].Text);

            Session["Data"] = dt;
            Response.Redirect("WebForm2.aspx");
        }
    }

<form id="form1" runat="server">
   <div>

       <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" Height="310px" Style="margin-right: 56px" Width="704px">
           <Columns>
               <asp:BoundField DataField="Title" HeaderText="Title" />
               <asp:BoundField DataField="Date" HeaderText="Date" />
               <asp:BoundField DataField="events" HeaderText="events" />
           </Columns>
       </asp:GridView>
   </div>
   </form>

 public partial class WebForm2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack) {
                DataTable dt = (DataTable)Session["Data"];
                GridView1.DataSource = dt;
                GridView1.DataBind();
            }

        }
    }
}