Zip is a compression program. Most PC's come loaded with some form of a compression program. Usually you can go to the desktop, right-click, and from there you will locate something called compression. However, some of us inadvertantly remove, lose, whatever, that option for various reasons (in my case it was stupidity and a nasty little bugger). If all else fails you can go to the link listed below and download a trial version of WinZip. It is good for 45 days before you have to buy. After 45 days it doesn't stop working but, you do get those gosh awful little nusiance screens and pop-ups remind you it isn't free.
WinZip® - Download Evaluation Page
The link below is for a different compression software program. It has gotten some good reviews and write-ups in different mags. Should be good for almost all OS's. Just be sure to read the directions. LOL, did I really just say that!
ZipGenius.it - Free zip utility for Windows that handles zip, rar, cab, 7-zip archives and CD-ROM ISO9660 image files