[Satcomer]

To encrypt something (per se) is easy. Open /Applications/Utilities/Disk Utility and click on "New Image". When the drop down window appears, select the "Encryption" tab and choose to encrypt. This will create a new temp disk image (it will be a example.img type file that makes a temporary disk image) and the temporary hard disk will appear. Backup to that temporary hard disk with a backup program like SuperDuper or Carbon Copy Cloner or others. Once you write to that temporary hard disk, it automatically write to the .img file. Once you are done writing to the temporary hard drive (note: you better make it big enough, but to big to overwrite it for CDs/DVDs), throw the temporary hard disk away. Now in Disk Utility, select the .img file you made (in the Disk Utility program) and in the Disk Utility menu, burn the img.

Congratulations, you made an encrypted backup.