Hello and welcome,
Thank you !
You could use : "System" tab -> "WinReducer Post Installation" tab -> "OOBE" tab ... Then you could use the "ADD" button to add your executable (everything will be done automatically = your executable file will be copied in the appropriate folder and a line will be added in the window to launch it).
But take care at 3 points :
1) It seems that the OOBE tool is a little buggy (I will work on it tomorrow and try to solve this for v1.12)
2) This method will not work for entire folders (like office 2013) -> but I will add support for this in v1.13 (I'm already working on it
3) If you want to use software silent switches, you need to add them manually at the end of each software line
EDIT : I will rework the Tutorial forum part sooner !