You can use Disk Utility to create an encrypted .dmg
The also is a way using Automator see this...
I've seen several options on-line in non support comminuties about using termnial to encrypt files but is that the only true option on MAC's? I'm trying to send a compressed/zipped file and then password protect or encrypt it. I have tried the terminal option but have had zero success.
The best part about ZIP file encryption is that you never have to worry about your data. If you lose the password, it is very easy to decrypt.
The first thing to do is find out what decryption capabillities your recepient has. You can create an encrypted ZIP file in the Terminal with "zip -encrypt file.zip sensitivefile.doc". ZIP just isn't secure at all. You would only do it because someone asked you to and you want to make them feel better.
How sensitive is this data you're sending, and what kind of systems are the recipients using? As etresoft points out, the encryption in zip files isn't particularly good. The encryption on a .dmg file is quite good, but that's not an option if you're sending to Windows users.
If the intent is to send truly sensitive data via e-mail, the best option would be public key encryption, which involves each party getting a certificate from a trusted certificate authority and exchanging public keys. You can easily encrypt a file to anyone whose public key you have, and the only one who can decrypt the file is that person. For more information, here's a tutorial that looks pretty good:
There is no built-in, cross-platform GUI tool for encrypting files in OS X. If the file you want to send is small enough to email, or if you can break it up into pieces that are small enough, then S/MIME is a good option, but it calls for some preparation at both ends.