If myDir is the directory of your project, the resources' file has path myDir\Properties\Resources.resx.
Now, when you execute a program from Visual Studio in Debug mode, the folder is myDir\Bin\Debug.
You have to go up 2 folders and enter the Properties folder:
var resourcesFileName = "Resources.resx";
var currentDirectory = Directory.GetCurrentDirectory();
var actualResourceFilePath = Path.Combine(
currentDirectory, "..", "..", "Properties", resourcesFileName);
var desktop = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
var newFilePath = Path.Combine(desktop, resourcesFileName);
File.Copy(actualResourceFilePath, newFilePath, true);
I suggest you to not use the path separator in the hard-coded way (@"dir1\dir2...").
Use Path.Combine
instead.