What argument should be in this missing part of formatter.Serliaze to get the program to save just the program as a .exe?

Ignore the Openfiles.

class FileOption
{ 
    OpenFileDialog openDialog = new OpenFileDialog();

    SaveFileDialog saveDialog = new SaveFileDialog();

    BinaryFormatter formatter = new BinaryFormatter();


    public void Open()
    {


    }

    public void Save()
    {
        if (saveDialog.ShowDialog() == DialogResult.OK)
        {
            FileStream file = new FileStream(saveDialog.FileName, FileMode.Create);

            formatter.Serialize(file, x); // x means that i havent set anything there yet//
            file.Close();
        }
    }
}