zip -er test.zip MyFiles

From man zip

-e
--encrypt

Encrypt the contents of the zip archive using a password which is entered on the terminal in response to a prompt (this will not be echoed; if standard error is not a tty, zip will exit with an error).  The password prompt is repeated to save the user from typing errors.

-r
--recurse-paths
Travel the directory structure recursively

-P
--password password
Use password to encrypt zipfile entries (if any).  THIS IS INSECURE!

zip -er -P mypassword test.zip myFiles