include decimal places 1500 and leave it as 1500.00 without comma!

I have an integer value of 1500 in the variable valuemonetary and I want to send it to another valuevalue variable like 1500.00. How to do in C #. I've tried conversions and nothing happens ... In the end, the variable ValueDecimal should be filled as 1500.00. I made many forms and nothing happens. I do not know what to do. Part of the routine is this;

                string valorreceb = ((registro.Cells["Valor"].Value.ToString()));
                valorreceb = valorreceb.ToString().Replace(".", ",");
                if (string.IsNullOrEmpty(registro.Cells["Valor"].Value.ToString()) || valorreceb == "0")
                {

                    String valor2 = "0.00";
                    cepXml.AppendFormat("\t\t<Valor>{0}</Valor>\r\n", valor2);
                }
                else
                {
                    decimal d = Convert.ToDecimal(valorreceb);
                    string Valordecimal = Convert.ToString(d);
                    string sVariavelNova = Valordecimal.Replace(",", ".");

                    cepXml.AppendFormat("\t\t<Valor>{0}</Valor>\r\n", Valordecimal);
                }