How do you lock a folder with a disk image?

Since I started using a mac, I found I can't lock up my porn in a locked folder any more. I have to an create an encrypted disk image and use that somehow. I created one, but I don't know how to use it to lock a folder. It's probably simple. Can someone take me through it, step by step?

 

Here's a slideshow of how to encrypt a folder with files in it. (create and use a password to get to the files in folder.)

http://www.flickr.com/photos/penmachine/sets/72157594167748426/show/

*edit*
Making an alias makes things really easy for you to copy stuff into the folder. Also, makes it easier to access.

 

cool! Thanks! I think I got it now.