KBlackbox is part of the KDE project http://www.kde.org/.
KBlackbox can be found in the kdegames package on ftp://ftp.kde.org/pub/kde/, the main FTP site of the KDE project.
In order to compile and install KBlackbox on your system, type the following in the base directory of the KBlackbox distribution:
% ./configure % make % make install
Since KBlackbox uses autoconf and automake you should have no trouble compiling it. Should you run into problems please report them to the KDE mailing lists.