Think of the chord between the wingtip and the tip of the spoiler when extended.
If you then draw the relative wind (a little under horizontal when in ground effect I'd suppose) you will see the new chordline will have a negative AOA when flying horizontal or at a slight negative angle.
The effect will be pressure buildup on the top surface of the wing, creating downforce.
Helldogbe, not how it works at all I'm afraid. All I can suggest is a bit of study on aerodynamics, as it would consume too much space here to dispell the errors in your explanation.