I was never a STOS coder (always prefered GFA), but I can give you some general points:
a)Show physical screen
b)Draw in logical screen
Other than that, you're on your own (from me
Why not trying to find a STOS manual (I think there was a book called "Your 2nd STOS Manual"???). Also, I think that the e-mag Ictari has lots and lots of STOS source.