How do I download ROMs?

I'm completely new to the world of ROM hacks, and I've always wanted to play games like Pokemon Sweet version and Pokemon AshGray. I've tried a couple times to figure out if I need to get something specific in order to actually play the games, but I'm a little scared of all the illegitimate links. I don't want to screw up my dad's laptop by trying to get a game and instead getting a virus. (if you're so kind as to answer, please use basic terms. I'm a 14-year-old who doesn't understand anything)

Sorry friend, but this really isn't the place to ask about this kind of stuff. There are tutorials if you look around the ROM Hacking section, and I'm sure someone there would be happy to help you, but this section (M&G) is about introducing yourself to the community. If you want, you can definitely edit this thread or start a new one to tell us more about yourself! :)