How to create a folder(in a program files subfolder) I can create a file into with a custom action ?

[amapic]

Hi,

I would like to create a a folder located in a subfolder of "program files" like this : 

C:\Program Files (x86)\X/Y/Z

I would like to create files in this folder by a custom action contained in the same installshield.

Thirdly, How to be sure that any other program can create files into this folder ? How to set up permission for this ?

Thanks for your help.