Escribir en un fichero

StringBuilder sbFile = new StringBuilder();
StreamWriter swWriter;
string fileName;

sbFile.Append(sDirLog);
sbFile.Append(@"Name");
sbFile.Append(".log");
fileName = sbFile.ToString();
swWriter = File.AppendText(fileName);

swWriter.WriteLine(System.DateTime.Now.ToString("dd-MM-yyyy") + " " + System.DateTime.Now.ToString("Texto");
swWriter.Close();