Copy the files from the memory stick to the BK6 data folder on your laptop's C drive. If you then modify your data on the laptop you will have to do the reverse to transfer it back to the desktop. This obviously has it's drawbacks but it works.
Alternatively, from the opening screen of BK, press control+O. Then in the window that opens, navigate to the memory stick and the data folder thereon. This too has it's drawbacks as the memory stick and the computer you are using at the time must be together.
I recommend the first method but preferably do all of your data entry on one computer and use the other only for viewing. That way you minimise the chance of mistakes.