This is a typical example of just one of the many notes you will be given to accompany each tutorial or workshop (designed for Photoshop Elements):
Open the image landscape. As you can see, the sky is very flat. Click Enhance>Auto Levels. This removes the dullness from the photo.
Create an Adjustment Layer
First make sure that the Layers palette is visible on screen. If it isn’t, click Window>Layers.
Move the middle slider to the right until the sky is considerably darker (ignore what the change does to the rest of the photo). Click OK.
Adjust the image so that only the sky is darker
Click on the Gradient Tool in the toolbox on the left of the screen. In the Tool Settings bar near the top of the screen, an example of the gradient will appear. It should be graduated from white to black. If it isn’t, click on the tiny drop-down arrow next to the example and choose the gradient in the top left-hand corner.
If you’re not entirely happy with the result, you can double click on the Layer Thumbnail in the adjustment layer and readjust the sliders until you achieve the desired effect.
The adjusted image has a considerably stronger-looking sky, with more variation in colour and cloud detail.