Magnetism is pretty cool. It’s kind of hard to understand, so I’m going to explain it to you.
Unlike most other chunks of matter on this earth, all of the electrons in a magnet spin the same way. This makes a force that is called Magnetism. In a magnet, there are these things called domains. In most substances, they are in a jumble and not in line. When you magnetize something, it makes all of those domains get into line and become a magnet.
To magnetize a nail, for example, you would take a magnet and your nail, and rub them together. After you do this for a while, try to pick up another nail with the one you magnetized. If it doesn’t work, then you need to magnetize it some more. Eventually, the nail will become a magnet!