Moding skies

[Mandinga91]

Hi im mandinga and im new..i have been reading the page and i liked ,so i decided to join..Im a huge fan of vice city,and i started a proyect moding my vice city based on the universe of matrix ,and for now everything was fine..but i want to do a new modification and i dont now how..i changed the colour of the rain,also the skin of tommy vercetti and a lot of things more,but i wanted to change the color of the sky in game to green(just like in the movies)..so i will ask you:

Do you know which files i should change or replace,or what programs i should download?

if someone knows,please ...

Thanks!