- The fact you have said 'the code in her box' really answers your own question. You need to have access to the box and therefore you need to buy one of the Barbie dolls that comes with the codes to be used on Barbie.com.
You may well find a few codes online if you search hard enough, but this is not recommended as you may well be wasting a lot of time for no reward. This is because the codes can only be used once and so the majority of people who buy the Barbie doll will obviously want to use the code themselves.
Therefore, the very limited amount of generous people who may put their unwanted code online will have it snapped up and used straight away by someone else.
This will leave many codes on websites that are no longer valid and so you could spend hours typing in codes to then find out not a single one works. So as you can see the best way to get a code is to actually buy the Barbie doll yourself.
It may be the more expensive way to do it but of course you get the doll as well and save yourself a lot of frustration and hours of trawling through Google.com.