Instructions and user guide of Inno Setup

[BelGiaguaro1980]

I used the package ISTool to do this...I can also edit already created a setup with inno setup? in particular, I downloaded a game and would like to modify some parameters of the setup (like wallpapers or icons)...the setup of the game in question was created with Inno Setup by group KapitalSin...I make these changes? how?