When I defrag my laptop's C drive, it wont do anything to it except rearrange it right?

If you are worried that something will end up damaged or lost if you defrag your drive, don't be!! Nothing will happen that is bad, in fact your computer's performance should improve somewhat, What happens is over time the files that are constantly being read and written to the hard drive become scattered accross the drive. Your computer then has to search for the file every time it needs to read the info from it. this slows down thee performance. All defragging does is rearrange the files in a more logical order so the computer can find the file it looking for much quicker. A good defragging program is Auslogics Disk Defrag. You can download it for free from the net.