Just downloaded

Try to play games with other SPers, so you can ask them things mid game and they can give you tips mid game. I say look at some champions and their skills (450+free week ones) and see if they look interesting, if they do try them out. Also as Kasso said try not to just mindlessly attack the minions, but just walk around and attack them the second they have low enough health so you can one hit them and get all the gold. That will already put you far ahead most other new people.