At the first cannon go through it
approach the second cannon then go through the second one from the other side
then go to the third cannon (you will have to battle a trainer here) then go through the cannon (there will be another trainer)
then its kinda hard to see but on the side of this cannon there is another way the cannon will shoot you (that is where I got stuck the first time)
from there though everything is pretty simple there will be two more people then you can battle then Skyla
