As far as I understand and hopefully others with more experience will chime in, the live rock is your biological filter and the sump can act like your mechanical filter. But if you don't want to use the sump, you can use the canister filters such as Fluval 405. This will be your bio and also mechanical filter. With this type of filter, you need to clean it regularly, at least once every two weeks. Open it up in a month, and you see a lot of muck and it smells bad
But I think a sump is best, there you can throw in a lot of good stuffs, and avoiding to hang them behind the tank. Or instead of the sump, you can do a refugium, it's similar to the sump but it gives you room to grow macro algae. It's fun to watch little tiny things moving around in this space. This is to remove your nitrate.
But what important is start with a tank with only live rock, set everything up and let it run fishless for a few week. Dont put in demsel, because later on it would be a nuisance, and you cannot take it back out. People told me to throw in a piece of shrimp or a dead clam once in a while to help speed up the cycle. After a week or two, put in a pair of clown fish. they're hardy and help cycle the tank, they're not expensive and they are a nice addition in the tank.
I don't mean to talk like a pro, I am not
I'm new like you, and I know, you can't just read and read, and get nowhere. You got to start somewhere, might as well, learning while doing it. Just be careful, don't rush things.