You can play kennen on the top or mid lane.
You need to make sure that your cs is higher than your enemy like always.
Because kennen don't have mana but have energy it is realy easy to herase your enemy, but make sure when u herase on the top lane there is always a ward on your side so u can see income the jungler of the enemy.

when You did finish your build you need to sell your dorrans shield for the Zhonya's, this will give u back some mana and i nice passive what u realy need in the late game.
This passive is important because when enemy's see what damage u make they will gonna focus.
They way you use your passive is verry easy you need to use it when your ulti is on. It is also easier when u have flash so you can flash i the enemy's before you cast your ultimate.

*make sure the flash is nerved and it isn't that long annymore!