XML : Error when saving an XML file

I writing app for windows phone.

I try to make creation and saving of xml file.

I made creation

Here is my code

   XmlDocument doc = new XmlDocument();          XmlElement el = (XmlElement)doc.AppendChild(doc.CreateElement("Order"));          el.SetAttribute("CallConfirm", "1");          el.SetAttribute("PayMethod", "");          el.SetAttribute("QtyPerson", "");          el.SetAttribute("Type", "1");          el.SetAttribute("PayStateID", "0");          el.SetAttribute("Remark", "{StreetName} , ..");          el.SetAttribute("RemarkMoney", "0");          el.SetAttribute("TimePlan", "");          el.SetAttribute("Brand", "1");          el.SetAttribute("DiscountPercent", "0");          el.SetAttribute("BonusAmount", "0");          el.SetAttribute("Department", "");            XmlElement el2 = (XmlElement)el.AppendChild(doc.CreateElement("Customer"));            el2.SetAttribute("Login", "");          el2.SetAttribute("FIO", "{FIO}");            XmlElement el3 = (XmlElement)el.AppendChild(doc.CreateElement("Address"));            el3.SetAttribute("CityName", "");          el3.SetAttribute("StationName", "");          el3.SetAttribute("StreetName", "{StreetName}");          el3.SetAttribute("House", "{HouseName}");          el3.SetAttribute("Corpus", "");          el3.SetAttribute("Building", "");          el3.SetAttribute("Flat", "{FlatName}");          el3.SetAttribute("Porch", "");          el3.SetAttribute("Floor", "");          el3.SetAttribute("DoorCode", "");            XmlElement el4 = (XmlElement)el.AppendChild(doc.CreateElement("Phone"));            el4.SetAttribute("Code", "{Code}");          el4.SetAttribute("Number", "{Phone}");            XmlElement el5 = (XmlElement)el.AppendChild(doc.CreateElement("Products"));    

For save I try to do this var documentsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal); var filePath = Path.Combine(documentsPath, "myFile.xml"); doc.Save (filePath);

But Visual Studio show errors.

  Error   CS0117  'Environment' does not contain a definition for 'GetFolderPath'         Error   CS0117  'Environment' does not contain a definition for 'SpecialFolder'    

How I can save my xml file?

Thank's for help.