You deleted everything from your USB key or a drive, so there should be enough free space to copy the new files, but you still get the not enough free space message in Mac OS X? This is what you need to do.
If you are tired and annoyed by the app requests and notifications your friends keep sending on Facebook, this is how you get rid of them without having to unfriend your friends.
The new iOS 7 comes with an interesting moving background motion or a so called Parallax Effect when you physically move your device about. Let me show you how to turn it off to improve battery life.