You need to find 4 hidden objects within 4 seconds. This is pretty easy if you use a guide.
Or you can simply take your time around the puzzle and find 4 objects that are near each other. Don't click on any yet! Once you found 4 objects, start quickly clicking on each of them. Should come without trouble.
Here is a good walkthrough with pictures to help you along the way.
http://www.bigfishgames.com/blog/walkthrough/nightmares-from...