The negro leagues download is a zip file.  You'll need a zip
utility to unzip the files.  There is a free one available
at winzip.com.  Install the winzip utility, then double
click the negro_disks.zip file in windows explorer.  the
winzip utility should
open, select EXTRACT.  you'll need to choose a directory to
extract to, I would choose C:\BBW\negro or something.  i am
assuming your apba is installed in C:\BBW, the default
directory.  one you extract the files, close winzip.

then open up league manager.  all the negro leageus are
stored as *.bck files, or "backup" files for abaseball for
windows.  in league manager, go to the top menu, under
SELECT, choose RESTORE ORGANIZATION.  in that dialog, find
the C:\BBW\negro folder (or wherever you saved the files),
and select one of the .bck files, and click OK.  that should
restore that file.  you'll need to repeat this step for each
of the .bck files (about 8 files) for all the leagues.