Migration problems (filevault)

I have a MacBookPro 15 (2007) that just broke down. The hard drive is ok though but can't access it for the moment. So I bought a new one and when trying to migrate the files using my TimeMachine backup I get an error message, and it's because I realized that the files are encrypted, because FileVault was activated in the old Mac.

Question is: how can I recover the files in that situation?? Thanks so much.