If you are baffled by Curves, what it does and how to use it, Amanda at Everyday Elements has a really helpful tutorial written for both PS and PSE. She has a written step-by-step on her site as well as a video tutorial at the end. It not new, but I found it to be very clear, concise and helpful!
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Working with the histogram, correcting the white and black balance is an important part that really makes a difference in the look of a picture. Many find it too much to use Camera Raw which also does these corrections. But for Photoshop Elements the user does not have a choice. They have to learn how to work with adjustments to correct the white balance and the curves.
Good tutorial.