1. Navigate to the file or folder you wish to encrypt.
2. Right click the file or folder, and choose Properties.
3. On the General tab, click the “Advanced” button.
4. Check the box labeled “Encrypt contents to secure data” and click OK
5. In the Properties window click OK. If the file is located in an unencrypted folder, you receive an Encryption Warning dialog box. Use one of the following steps:
6. If you want to encrypt only the file, click “Encrypt the file only”, and then click OK.
7. If you want to encrypt the file and the folder in which it is located, click “Encrypt the file and the parent folder”, and then click OK

Note: Files or folders cannot be encrypted on a volume (e.g., hard disk drive) that uses the FAT file system. File (and folder) encryption is only supported by the NTFS file system. Store the files or folders that you want to encrypt on NTFS volumes.

If another user creates a document in an encrypted folder, that document is encrypted allowing (by default) only that user to gain access. Because of this, a folder that you encrypt may contain files that you are unable to open. If you require access to these files, request that your user account be added to the list of users with whom the encrypted files are shared.

To set up FileVault on your Mac OS X computer:

(Encrypting files in OSX requires the use of FileVault)

1. Choose Apple menu > System Preferences and click Security.
2. If the Security preferences pane is locked, click the lock icon and type an administrator name and password.
3. If the Security preferences pane shows that a master password has not been set, click Set Master Password and type a password in the Master Password box.
4. Type the password again in the Verify box.
5. Type a hint in the Hint box to help you remember the password.
6. Click OK.
7. Click "Turn on FileVault" and read the message that appears. If you want to continue, click "Turn on FileVault" in the dialog, or click Cancel to stop.