When you go to battle.net and login with your battle.net account you will see a big green button on the right which says: "Acticate gamekey". Hit that button and enter the gamekeys you got with your battlechest.
It sounds as though you started a new account with your battlechest rather than upgrading the starter edition. WoW2 is your battlechest, WoW1 is where your characters are.
You'll need to contact Support to get the 2 accounts merged.
I'd go with this too. Contact our support team using the link above and they will help you correct the upgrade.