Oops it seems I spoke too fast
Third time's a charm. I reformatted and untared under Linux, did the changes directly in VI (and not under windows with an ext3 driver) and I am able to run a script and display an image now!
What's the next step? I will need help to install Python I guess. In the meantime I will learn Python
not one of my languages but I learn fast. I will try to start with a simple script (write the date in the middle of the screen for example).