Right, I think I am a step further now..quite close to the end....
my problem is that I cannot change the color of the pixel on the very top left (0/0)..its always black....doesn`t matter whether I click on 'edit colors' on paint.exe. And even when I tried it with the black pushpin, which was supposed to work out then, I wasn`t successful..nothing happens..nothing in the black pushpins ain`t transparent....