If youre on euw add me ign: SweatySeagull

Play Vs Al till about lvl 10 on 5 vs 5
Then from lvl 10 - 15(20) play dominion normal
Then from 15 to 30 it will be 5 vs 5 normal

Tip's :Try not to buy that many champions before lvl 20.
When you hit lvl 20 buy runes for your rune page's (Only tier 3 runes)
When you play with runes at around lvl 20 it will give you a slight advantage over the other players.

Some people say that you should start 5 vs 5 when you hit lvl 10 but i think its better to start at lvl 15(20) because you shall have more point to put in masteries.

And if you need anyhelp with builds try this site [ Register or Signin to view external links. ]

Or dont understand the rules of the game here read this
Guide

Hope this helps you to get started.