Are you saying you've downloaded a copy of Windows 7 Utimate Black edition and are wondering if you can overwrite a Vista 64 bit system?
If you've got a 64bit copy of this "windows black" then yes, shouldn't be a problem.. And you install by burning your downloaded copy (a legally downloaded copy of course) to a disc and then booting your computer with the disc in the drive. Then continue to follow instructions.
If you haven't got a 64bit copy and have instead downloaded a 32bit copy, you might have issues (as your laptop came with a 64bit version, it was probably for a reason).
Give us some more information and we might be able to help.