thanks for the help skippy.
To hide an image, you will want to wrap it in a 'spoiler' tag:
[ spoiler]text or image to hide here[/spoiler]
(Don't copy/paste that example though: I had to use a special character so that it would print the actual tag)
Skippy, how do I set up the NSFW tags to hide a picture post?....i don't understand how to do this.