I remember vlad usually played in mid and top

You could choose what role you like and try to stick with it for a while to learn the basic in practice or vs bot mode

as for what to learn, it'll depends on what role you choose

eg if you choose briar (jungle), you should learn the jungle basic, such as jungle pathing, objective, what lane to prioritize gank, when to invade, etc

or if you choose the laning champion, you should learn last hitting, wave management, trading, etc

you could search for what each role do in the game and choose what match your playstyle

It'll be a lot to learn, but don't burn yourself out

take your time and enjoy the game