The filename suggests that you downloaded the source file probably from cups.org. That will need to be compiled on your system before it can be installed. Slackware has prebuilt cups package in the extras directory for at least 8.0 and 8.1 I think. Also, either of these require a second package, "espgs", or the ghostscript modules for the CUPS to work as well. That is also offered in the extras directory. I think the second package started with CUPS version 1.1.13 if I recall.
For the Slack packages just run "pkgtool" from your download directory in a shell console and it will detect the packages and install them for you. Prebuilt.
After pkgtool installs the packages, you should find documentation in the /usr/doc/cups-1.1.15 directory for Slack 8.1. And I think it installs a startup script as /etc/rc.d/rc.cups. You can execute it manually the first time, after that it should execute when you boot. Use "/etc/rc.d/rc.cups start" to get it loaded the first time.
To configure it, point a browser to to http://localhost:631.
It should bring up the main menu. It can be done at the command line also. The docs will explain that operation better than I can.
Of course you have to be logged in as root for all of this. Unless you have experience building and installing from source I would recommend the Slack packages at least for the first time. Once you have it installed and know it is working then try to build your own if like.