help in customizing from scratch inno setup installer

[DGRPK]

Hello to all the forum, have intermediate to compress games, but what I want to know much more is getting to fully customize to your liking and not be used from scripts that exist only change images and ready, I would like to know which lines are have to take into account for example to change the location of the buttons, the buttons change from default, fully customize the wizzardfrom from the length and breadth of the installer, change the color of the progress bar and change the installation Color same texts, I saw very good scripts here in the forum, but I want to be able to customize my next project from scratch, I hope your help.