Moving the drawing origin to the bottom left corner

[Polaris431]

I have spent hours through newsgroups and googling but I am at a loss
how to move the drawing origin from the top left corner to the bottom
left corner and have Y values increase towards the top.

All the stuff I find shows stuff like this:

private void Form1_Paint(obj ect sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
Pen pen = new Pen(Color.Blue) ;

Matrix mm = new Matrix();
mm = new Matrix(1, 0, 0, -1, 0, 0);
g.Transform = mm;

g.DrawLine(pen, 0, 0, 100, 100);
}

But nothing gets drawn. What am I missing?

Thanks
Johann