How does the data get put on a hardrive?

if I'm right about this, hard drives work on magnetism. there is loads of magnets on a 'disk' in the hard drive box. the data gets put on the hard drive by magnetising the magnets(so that's why you can't go near them with magnets, it will simply wipe your drive). it's probably done by the binary code or something similar with two possible outcomes as magnets only have two polarities. it is then read by some sort of reader. if you've seen one when it's working (took apart) a disk spins and a little lever thing moves around quickly on it.

hope that helps, i doubt it though