This is fairly straight forward yet people find it somewhat confusing. Follow these easy steps below or if you need more help, use the Linux manpage.
How to Zip a file(s)
_The Examples shows how to zip a single file and multiple files into a single .zip
zip photo.zip photo.jpg
zip photos.zip photo1.jpg photo2.jpg photo3.jpg
How to Zip an entire Directory
The Example shows how to zip a directory called photos into a zip file called photos.zip
zip -r photos.zip photos
How to Unzip a .Zip File
unzip photos.zip
How to list contents of a .Zip file without Unzipping
unzip -l photos.zip