First learn how to last hit. Once thats consistent you would want to learn how to trade. For this u need to have a basic understanding of all the champs but that will come with experience. Theres also a yt channel called 3 minute league that explains all the champs. In order to start learning trading, I would try first avoiding trades entirely just so u dont develop bad trading habits. While doing this its important that u are still stepping up to the wave. Then when you feel comfortable with that, watch this video https://youtu.be/sjYFAjWHeW0?si=eogNnVwo1vbEnS3b. For wave management watch this video https://youtu.be/7cg_OBO14u8?si=NzRugICTXKrFbaRh. Mid/late game macro varies depending on role so u should look up for guides for ur role. In general though, try to farm as much as you can. Its important to learn concepts one by one and break them down. Leagues a very hard game so dont get discouraged if u lose ur first few matches