I'm not going to lie, if you are playing league for the first time you are going to hate it because you will die a lot trying to figure out how to get used to the champions and the play style. Not to mention the higher level players creating low level accounts who will completely destroy your hopes and dreams. The best advise I can give is stick it out if you are new, get to level 30 and you will become experienced and learn how to make better decisions during each game.
When you reach level 30 you can play ranked games which will be way more competitive than when you are playing for fun. The ranking system goes from bronze, silver, gold, platinum, diamond, (they just recently added Master), and then the final rank which is Challenger. I was able to reach gold this season which I am happy with knowing that in the future I will only improve.