I know the basics of Linear algebra with matrixes etc. But one questions remains is how this tutorials had gotten this

 private void SetUpCamera()
     Matrix viewMatrix = Matrix.CreateLookAt(new Vector3(0, 0, 40), new Vector3(0, 0, 0), new Vector3(0, 1, 0));
     Matrix projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, this.Window.ClientBounds.Width / this.Window.ClientBounds.Height, 1.0f, 50.0f);
I was just wondering how do I go about setting up the camera in XNA. And how he gotten those points.