To uncompress the files, get the GNU gunzip program. It is available for DOS, Mac, and Unix platforms. On Windows 95 and later, use WinZip.
To view the files, use the GNU ghostscript or ghostview programs. They are available for Mac, Win95, and Unix platforms. (On Win95 and WinNT the name is gsview.) Look here for Unix and Windows versions.
To print the files, you'll need a postscript printer. In DOS, if your printer is attached to the parallel port, you can just copy the postscript file directly to the printer port: copy file.ps lpt1: If the printer is shared, you'll want to monitor it to be sure the output looks right (nice-looking text as opposed to seemingly random patterns of letters and numbers in the standard font). On the Mac, you can use the SendPS program to send a postscript file to your printer. On unix, if your system is configured properly you should be able to type lpr -Pprintername file.ps
All of the programs (gunzip, sendps, etc) I mentioned are (or at least were) available for free somewhere on the internet. Look for them at www.shareware.com or use a search engine like www.google.com to find them.