Hi Ali,
I'm not sure I understood your problem correctly, but if you're trying to specify folders to be created when you distribute your app, the trick is to press the INS key after having selected your INSTALLDIR in the "Destination computer's folders", in "Specify Application Data" subsection, or right-click in the desired target folder and select "Add".
Hope it helps!
Pascal Marier-Dionne
Québec, Canada