display Gridview checkbox selected values in label on next page after submit button click

Set AutoPostback property of your grid checkbox to true and create selected index changed event of your checkbox and store the selected item in Session. Now when you go to the next page you can refer selected value from session. Find below code sample for the same kind of functionality :

ASPX Code :

<asp:GridView runat="server" ID="gridMain" AutoGenerateColumns="False" OnRowDataBound="gridMainRowDataBound">
        <Columns>
            <asp:BoundField DataField="EmployeeName" HeaderText="Name" />
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:CheckBoxList runat="server" ID="checkDivisions" AutoPostBack="True" OnSelectedIndexChanged="divisonChanged"/>                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>

ASPX.cs Code :

public partial class About : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                this.BindGrid();
            }
        }

        private void BindGrid()
        {
            var empList = new List<Employee>();
            for (var i = 0; i < 5; i++)
            {
                var employee = new Employee
                                   {
                                       EmployeeName = "Name_" + i,
                                       Divisions =
                                           new List<Division>
                                               {
                                                   new Division
                                                       {
                                                           DivisionName = "A",
                                                           DivisonID = "1"
                                                       },
                                                   new Division
                                                       {
                                                           DivisionName = "B",
                                                           DivisonID = "2"
                                                       },
                                                   new Division
                                                       {
                                                           DivisionName = "C",
                                                           DivisonID = "3"
                                                       }
                                               }
                                   };

                empList.Add(employee);
            }

            this.gridMain.DataSource = empList;
            this.gridMain.DataBind();
        }

        protected void gridMainRowDataBound(object sender, GridViewRowEventArgs e)
        {
            var divisonList = e.Row.Cells[1].FindControl("checkDivisions") as CheckBoxList;

            if (divisonList != null)
            {
                divisonList.DataSource = DataBinder.Eval(e.Row.DataItem, "Divisions");
                divisonList.DataTextField = "DivisionName";
                divisonList.DataValueField = "DivisonID";
                divisonList.DataBind();
            }
        }

        protected void divisonChanged(object sender, EventArgs e)
        {
            Session["LastSelectedItem"] = ((ListControl)sender).SelectedItem.Text;
        }
    }

    /// <summary>
    /// The empl.
    /// </summary>
    public class Employee
    {
        public string EmployeeName { get; set; }

        public List<Division> Divisions { get; set; }
    }

    /// <summary>
    /// The empl 2.
    /// </summary>
    public class Division
    {
        public string DivisionName { get; set; }

        public string DivisonID { get; set; }
    }

create a link button
in this
<asp:linkbutton id="LinkButton1" runat="server" postbackurl="<%#" ~="" guest="" default.aspx?id="+Eval(" uniqueid")="" %&gt;"="" xmlns:asp="#unknown">Add To Cart
///////////////////////////////////////////////////////////////////
then
on next page you can retrieve this value on labelid on page load like this

Label3.Text = Request.QueryString["id"];

try and let me know