There is actually a better method for protecting your files. Go to Disk Utility located here: Hard Drive/Applications Folder/Utilities Folder. Click the +New Image Icon located on the top of window. When the window pops up:

1.) Name the .dmg file that will be made. (Name it something that won't draw attention if you don't want people to get suspicious of what's in it. ie PowerStoreLib or anything that sounds like it might be a system file. Even if a person is smart enough to know that this is a .dmg and not a system file, they won't be able to search for names within the .dmg or open it without the password.)

2.) Choose the size of the .dmg (Tip - pre-plan for how large you might need this to be in the future. You can't change it after its made. You will have to create a new .dmg following the same process if you need more room. Also the encryption does take up a little room, so a 10mb file won't fit exactly in a 10mb dmg)

3.) Choose the AES-128 Encryption option from the pull-down menu. Set the password to something you will remember but is not easily guessed.

NOTE:
After you pick a password DO NOT ADD this password to the Keychain or you will have to start all over. Also DO NOT FORGET the password you set or you will loose all of the files that you put in there. You will not be able to open the .dmg after it is password encrypted without the password.

4.) Leave the format as Read/Write Disk Image.

That's it. It's really easy once you've done it a few times. Sig