how to send email with advertisement link with image (like amazon advertisement) and my message in seperate body in asp.net

            string to = txtemail.Text; //To address    
            string from = "samasp27@gmail.com"; //From address    
            MailMessage message = new MailMessage(from, to);

            string mailbody = "You like to book New Connection " + ddlcontent.SelectedItem.ToString();
            message.Subject = "Get Your New Connection";
            message.Body = mailbody;
            //message.BodyEncoding = Encoding.UTF8;
            message.IsBodyHtml = true;
            SmtpClient client = new SmtpClient("smtp.gmail.com", 587); //Gmail smtp    
            System.Net.NetworkCredential basicCredential1 = new
            System.Net.NetworkCredential("", "");
            client.EnableSsl = true;
            client.UseDefaultCredentials = false;
            client.Credentials = basicCredential1;
            client.Send(message)