First of all, welcome to the game!
It's always nice to see new faces.
The first step it to start building. I prefer to take all my troops over to the other side of the trees to build near the iron. Personal preference, it can likely be done either way. While the peasants are busy building the standard two quarters and an armory, I send the guy from my left tower up to the treasure, and then leave him there. I leave the guy in the tower closest to the enemy so that he doesn't send peasants to gather chickens in my area. I then set the rally point for my troops to be at the base of them mountain on his side.
When gathering supplies, focus primarily on iron, only gather enough stone to fill your towers and have a few left over. Send over about three or four peasants to your rally point as soon as possible, backing them up with berserkers when you get a chance. When they arrive, have them start putting up towers immediately. Keep building towers, starting out close to the trees then branching out to cover the entire base of his side of the mountain. Continue to send troops over, and fill towers as soon as they're completed. You will likely want to send over a few additional peasants to speed up the building process.
I've completed it with a much smaller quarters size, so by using that technique you should be able to complete it without a problem. Remember, if it feels like things are going too fast and you aren't able to deploy troops, put axemen in towers, and start building new towers quickly enough, just slow the game speed down.
Best of luck to you!