The game itself has a nice tutorial you should try out first. It gives you a general idea of what the game is like and how you play it, etc.
Otherwise, check up on some guides, they are really helpful sometimes.
I'm on EUW too, so if you ever want to play, add me ingame: Robin Hood
You can read the wiki page and search videos on youtube, there are plenty of guides you can find there. You can also find guides to different champions on mobafire or solomid (google those).
If you ever decide to join, play around with different heroes, see which one(s) you like/are good with, then master that one. its no good constantly rotating through 5-6 heroes.
I disagree with this. That's too many games playing with bots, which are really dumb AIs.
Anyways, just remember that this game takes years to get really good at. It's not something you get used to in a few months