Need pointed in correct diretion

Hi, I want to write an app that will restrict access to programs and folders based on the users login or if the parent prefers, it could be activated or deactivated by a set of key strokes (CNTL+SHIFT+F12) or something. This is for my wife's grandchildren. Kids are click happy and it sucks having to watch what they are doing. I figure that it would be a dialog-based app that will sit in the system tray (hidden if a kid is logged in). Will I need to use a system hook for the file open command? How will I know if a folder or program that I want do deny access to is the one being clicked? I think the hardest thing about programming is getting started...Thanks

I just thought of other potential problems.
If lets say I deny access to the Windows directory. Will programs that need information
from the system directory be able to get to it?
Conversely will the user be able to open let’s say Word and edit a file in the folder?

"Kids are click happy and it sucks having to watch what they are doing"

Care to explain before I help you....

Sally