Basic File Io C#

Open a file

OpenFileDialog openFileDialog = new OpenFileDialog();

openFileDialog.Filter = "Text files (*.txt)|*.txt";
openFileDialog.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

if (openFileDialog.ShowDialog() == true)
{
    //Do what you want to the file
}

Save a file

SaveFileDialog saveFileDialog = new SaveFileDialog();

saveFileDialog.Filter = "Text files (*.txt)|*.txt";
saveFileDialog.DefaultExt = "txt";
saveFileDialog.FileName = "database.txt";
saveFileDialog.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

if (saveFileDialog.ShowDialog() == true)
{
    //Do what you want to the save
}