public static GeneratedFile GenerateinvoiceXml(string authToken, string box, string tobox)
    {
        try
        {
            var content = new InvoiceInfo()
            {
                // заполняем согласно структуре InvoiceInfo
                InvoiceDate = "31.01.2016",                    // дата СФ
                InvoiceNumber = "11-012016-2410000000",                  // номер СФ
                Seller = {
                BoxId = box
            },
                Buyer = {
                BoxId = tobox
            },
                Signer = {
                SignerCertificate = ReadFileContent(FileWithCertName)
            },

                PaymentDocuments =   {
                    new PaymentDocumentInfo
                    {
                           DocumentDate = "08.08.2016",
                           DocumentNumber = "№00243015140"
                    }
            },
                Items = {
                new InvoiceItem
                {
                    Product = "Горячая вода (компонент на тепловую энергию). Прочие",
                    CountriesOfOrigin = { "23", "3243" } ,
                    TaxRate =  TaxRate.Fraction_10_110,
                    Subtotal = "321231"
                }
            },
                AdditionalInfos = {
                new AdditionalInfo
                {
                    Id = "2312321",
                    Value = "32423423"
                }
            },
                Total = "1000"
            };
            return Api.GenerateInvoiceXml(authToken, content);
        }
        catch (Exception e)
        {

            logger.Debug("Except{0}", e, null);
            Console.Read();
            return null;
        }
    }

Seller = new DiadocOrganizationInfo()
      {
        BoxId = box
      },
      Buyer = new DiadocOrganizationInfo()
      {
        BoxId = tobox
      },
      Signer = new Signer()
      {
        SignerCertificate = null
      },