The SaveFileDialog class defined in Microsoft.Win32 namespace represents Windows Save File Dialog control.
The following code snippet creates a SaveFileDialog, sets its default extension and fiter properties and calls ShowDialog method that displays SaveFileDialog control.
Microsoft.Win32.SaveFileDialog dlg = new Microsoft.Win32.SaveFileDialog();
dlg.DefaultExt = ".txt";
dlg.Filter = "Text documents (.txt)|*.txt";
if (dlg.ShowDialog() == true )
{
string filename = dlg.FileName;
}