This is just another reminder that OS X works just like other UNICES.
Imagine that you have a folder full of files. It’s called “grades.” You want to create a password-protected zip file of everything in that folder to send to your co-instructor.
Open a terminal window and navigate to the folder that is one level “above” the one that you want. For example, if your grades folder is located in /Users/bchapman/Spring Semester/, navigate to that folder.
Once in that folder, enter “zip -er Grades.zip grades/” and hit enter.
This will prompt you for a password. You will need to enter it twice. It will then create the encrypted archive that you can mail to your co-worker. They don’t need to know any fancy terminal kung-fu.
All of this comes from this article right here, where it’s explained better and with pictures:
This is a great way for you to practice your Terminal skills.