Add binary file from database to Zip file using Dotnetzip using C# .Net

hello,i have table and i save image into table format binarry,but i want zip this image that user can download multiple image from website

i wrrite this code but this code download one image......

 //string name = item.Name;
                    //string contentType = item.FormatImg; 
                    //Byte[] data = (Byte[])item.Image;

                    //// Send the file to the browser
                    //Response.AddHeader("Content-type", contentType);
                    //Response.AddHeader("Content-Disposition", "attachment; filename=" + name);
                    //Response.BinaryWrite(data);
                    //Response.Flush();
                    //Response.End();