I think this is probably the hardest one to put down in words since there is so much I would do. And obviously, I would do a lot more than what I'm writing here. But I would..
♥ Donate. Help people in need (put food on their tables and clothes on their bodies, etc).
♥ Pay off my families debts and give them whatever they wanted.
♥ Buy myself a beach house and a few apartments/houses around the world.
♥ Travel with my friends and family around the world.
♥ Literally shop until I dropped.
These five things are what I can come up with now. And like I said, obviously there is so much more I would do if I were the richest person in the world. It's hard to put it down in words and just come up with everything 'as we speak'. I think I would come up with things to spend the money on as I went. But ↑ are definitely something I would start with.
(I believe there might be people who don't like what I'd do, and maybe think my choices would be selfish, and that's fine. But you can always keep in mind that there's no way I'd ever be the richest person in the world, so stay calm!)