giving access permission 2 system folders/files in my Qtopia app

Hi guys,
   I wanted to know how i can resolve permission specifications for my
application.
I have developed a file browser application in Qtopia 2.2.0. I am using Red
hat enterprise edition 5.3.(to run x86-qtopia) 
     My code compiles fine. Also  i can access all files and folders in
/root/... or any user allowed areas.
but when i come to file system, I can't access system folders or files.
Initially i thought i had bugs in my code or i have mistaken in setting
paths. But soon i realised that this happens only with system
folders/files. I read a linux programming book in which i read about
initial permissions which can be changed by setting flags such as S_IRUSR |
S_IWGRP |S_XOTH etc. or i can use $chmod or $chown commands etc..
But i am confused as how i can use these flags or commands. As in where
should i write them so that my application can access all the files and
folders including system files and folders....
do i have to set these flags/permissions in the main of my application or
constructor?? If yes then do i have to keep on setting file permissions for
each and every file and folder???
Please guide!!!!

On the folder you want to copy to, do:
    ls -l
And if you don't have write permission to the folder, do this:
    chmod 777 your/folder/name
777 means permission to write, read and execute. If you want to tune it
better, search for it and choose a more appropriated number.

Sérgio

and how can we do that in c code?
I have no sys/stat.h header in my linux version