Using Session to store data from database using C# in ASP.Net

hi

I have OrderFilm.aspx that bind films information from database and I want use cookie in this page and users can order their film with different quality:

this is table:

Orderfilm.aspx

                <asp:DataList ID="DataList1" runat="server" RepeatColumns="2" RepeatDirection="Horizontal">
                    <ItemTemplate>
                        <div>
                            <asp:Label ID="lbldes" runat="server" Text='<%# Eval("name") %>'></asp:Label>
                            <asp:HyperLink ID="HyperLink3" runat="server" CssClass="LBP3In" NavigateUrl='<%#"film.aspx?ID="+Eval("ID")%>'
                                Target="_blank">click to order</asp:HyperLink>
                        </div>
                    </ItemTemplate>
                </asp:DataList>

in orderfilm.aspx users click on Film name and after that they go to film.aspx page that bind other film information from database :

film.aspx:

        <div>
            <asp:Label ID="lblMessage" runat="server" />
            <div>
                <asp:Label ID="Lblname" runat="server" />
                </br>
            <asp:CheckBox ID="cb720P" runat="server" Text="720P " />
                <asp:CheckBox ID="cb1080P" runat="server" Text="1080P" />
            </div>
            <asp:ImageButton ID="Imgorder" runat="server" AlternateText="order" OnClick="Imgorder_Click" />

        </div>

here users can select their intendend quality from checkbox:

film.aspx.cs:

string Film720p = string.Empty;
string FilmName = string.Empty;
string Film1080p = string.Empty;
protected void Page_Load(object sender, EventArgs e)
    {
        viewproduct();
        lblMessage.Text = GetCookies();
    }
    private void viewproduct()
    {
        string data1 = Request.QueryString["ID"].ToString();
        using (SqlConnection conn = General.GetConnection())
        {
            using (SqlCommand _cmd = General.GetCommand("viewFilm", conn))
            {
                _cmd.Parameters.AddWithValue("@id", data1);
                conn.Open();
                SqlDataReader _dr = _cmd.ExecuteReader();
                while (_dr.Read())
                {
                    Lblname.Text = _dr["name"].ToString();
                }
                _dr.Close();
            }
        }
    }

   protected void Imgorder_Click(object sender, ImageClickEventArgs e)
    {
        HttpCookie cookie = new HttpCookie("orderFilm");
        if (cb720P.Checked)
        {
            cookie["Film720p"] = cb720P.Text;
        }
        if (cb1080P.Checked)
        {
            cookie["Film1080P"] = cb1080P.Text;
        }
        cookie["FilmName"] = Lblname.Text;
        Response.Cookies.Add(cookie);
        lblMessage.Text = GetCookies();
    }
   private string GetCookies()
    {
        int i = 0;
        if (Request.Cookies["orderFilm"] != null || Request.Cookies["registerCity"] != null)
        {
            if (Request.Cookies["orderFilm"] != null)
            {
                FilmName=Request.Cookies["orderFilm"]["FilmName"];
                Film720p = Request.Cookies["orderFilm"]["Film720p"];
                Film1080p = Request.Cookies["orderFilm"]["Film1080p"];
            }
            if (!string.IsNullOrEmpty(Film720p))
            {
                i++;
            }
            if (!string.IsNullOrEmpty(Film1080p))
            {
                i++;
            }

            return (Film720p + " " + Film1080p + " " +FilmName+ "<br/>" + " Checked Count:" + i.ToString());
        }
        else
        {
            return "No Cookie !";
        }
    }

here I save cookie like this:

                FilmName=Request.Cookies["orderFilm"]["FilmName"];
                Film720p = Request.Cookies["orderFilm"]["Film720p"];
                Film1080p = Request.Cookies["orderFilm"]["Film1080p"];

I want if users click on film name from orderfim.aspx ( i.e:Spectre.2015 )and go to film.aspx and select 720P checkbox it save in cookie that users select 720P for  Spectre.2015 ...

here I wrote:

HttpCookie cookie = new HttpCookie("orderFilm");
if (cb720P.Checked)
{
   cookie["Film720p"] = cb720P.Text;
}
if (cb1080P.Checked)
{
   cookie["Film1080P"] = cb1080P.Text;
}
cookie["FilmName"] = Lblname.Text;
Response.Cookies.Add(cookie);
lblMessage.Text = GetCookies();

but  problem is that in orderfilm.aspx page if users click in other film name(i.e:WaterFalll) and go to Film.aspx page and checked 720p checkbox It delete their last selected cookie and just set their new cookie:

and attention that here I use querystring in orderfilm.aspx:

<asp:HyperLink ID="HyperLink3" runat="server" CssClass="LBP3In" NavigateUrl='<%#"film.aspx?ID="+Eval("ID")%>'
Target="_blank">click to order</asp:HyperLink>

I hope I can explain clearly...

how I can solve this problem...

Best regards

Neda