It might help to point out (or maybe I will be cursed for nit-picking - it would not be first time) but although they have a GPU, none of the MacBooks are Cuda-ENABLED when you buy them. You DO have to download the drivers, toolkit and SDK and set it up.
A former girlfriend once said I was unlikely to die of old age (the one that was Cooking-enabled but did not provide Cooking-support).
THere are some environment commands to set, but I suggest you follow the instructions on the installer screens and run through the other posts on this forum for help if you need it.