<FooterTemplate>
                                <asp:TextBox ID="txtName" runat="server" />
                            </FooterTemplate>

InsertCommand="insert (name,description,parentid) values (@name,@descr,@parentid)">

                    <InsertParameters>
                        <asp:ControlParameter ControlID="txtName" Type="String" Name="name" />
                        <asp:ControlParameter ControlID="txtDesr" Type="String" Name="desc" />
                        <asp:ControlParameter ControlID="GridView1" PropertyName="SelectedValue" Type="Int32" Name="name" />
                    </InsertParameters>

 using (SqlConnection connection = new SqlConnection(
                                               ConfigurationManager.ConnectionStrings["ApplicationServices"]
                                                                   .ConnectionString))
            {
                connection.Open();
                SqlCommand command = connection.CreateCommand();
                command.CommandType = CommandType.Text;
                command.CommandText = @"insert categories (name,description,parentid)
                                                    values (@name,@desc,@parentid)";
                command.Parameters.AddWithValue("@name", ((TextBox)GridView2.FooterRow.FindControl("txtName")).Text);
                command.Parameters.AddWithValue("@desc", ((TextBox)GridView2.FooterRow.FindControl("txtDescr")).Text);
                command.Parameters.AddWithValue("@parentid", int.Parse(GridView1.SelectedValue.ToString()));
                command.ExecuteNonQuery();
                
            }