If you have any friends who play the game, get them to teach you (play a few bot games with you to teach you the basics, make low-level smurfs to play normal games with you). Guides are great, but having someone there watching you play who can explain things to you and instruct you is invaluable. If you don't know anyone who does, don't worry. When you start playing normals, you'll be with two types of people: people like you who don't know how to play the game and won't judge you at the lowest levels (so don't worry about upsetting them) and smurf (alt, basically) players. If they rage at you ignore and report them, they're stupid for getting upset over new players for showing their inexperience; if they're that good their account's hidden rating will soar and they will end up playing other smurfs instead. I don't recommend playing bots for a long time, as you need to practise the game vs. other people your skill level, but a few games to learn the basics and practise champs doesn't hurt. Everyone starts somewhere, and if you perform poorly, your account's hidden rating will adjust to reflect that, so you will eventually be matched with people your own skill level; as you improve, this will increase, but don't worry about upsetting your teammates at the earliest levels. Don't be afraid to lose when you're just starting out, but do your best!