Here is a beginner to intermediate tutorial on how to use curves in Photoshop. Curves are feared by many, but they don't need to be. Colin will show you how they work in plain English
Many people shake with fear at the very mention of Curves. You don't need to fear anymore, because this helpful video will take the pain out of it. Watch as I explain in plain English how to use curves and bend them to your advantage. (pun intended).
Use Adjustment Layers whenever possible, because they are non-destructive. (Can be changed later).
Click the little finger icon to drag and adjust directly on the screen.
(With the Curves Modal Dialog only Ctrl+M/Cmd+M - Non Adjustment layers)
Hold down the Ctrl/Cmd key and click on a portion of an image to add a targeted point to the curve.
Hold Down Ctrl+Shift/Cmd+Shift to add points to the color channels of a curve.
If you like this tut, please check out Colin's DVD which contains over 7 hours of training just like this.