This pc is COMPLETE garbage. I would not even waste your money upgrading this crap.
But, if you mom says no, than maybe we can salvage it to last a little longer. just dont be expecting to play video games. I would start this process by reinstalling windows. There are a lot of things online about how to do that. (keep in mind, that reinstalling windows will DELETE ALL DATA!!!!!!) So after you reinstall Windows 7 (or whatever version you want) than you still wont be able to game, but you should be able to start learning to code. I would start with some light HTML, or Python programs (or whatever language you want to learn) and you can look up some stuff online and just write out some simple code. other than that, the PC wont be able to do much. Like i said, upgrading this pc now is a giant WASTE of money. its just so old, that there is no hope. But reinstalling windows should put the computer to "Factory Speed" by removing all the junk, cached files, ETC. ya ya ya, there are ways to remove all that junk without reinstalling windows, but trust me, simply reinstalling windows is MUCH MUCH easier to do, than hunt for cached files and deleting them, and all that crap.
PS:
you need to figure out how to explain to your mom that your pc is CRAP, and you cant do educational things like coding on it, because it is too slow!!!!!