Display the Layers palette with Window>Show Layers and you will see something like this:

Note the small triangle in the top right corner - clicking here allows you to add, delete or duplicate layers, along with other options. The same options are also available in Photoshop's Layer menu, and two of the icons at the bottom of the palette provide a third method for adding or deleting layers. As if this were not enough you can also delete or duplicate a layer by right-clicking its name. The above palette shows that a second layer called 'Statue' has already been added on top of the background layer called 'Sky'. New layers are always added immediately above the active layer so if you already have more than one layer you should think about exactly where in the stack of layers the new layer should be placed.

The eye symbol to the left of each layer indicate that both layers are currently visible - click an eye icon to hide the corresponding layer. The paintbrush icon and the fact that the Statue layer label has a dark blue background both indicate that the Statue layer is the active layer and that any changes will apply to this layer only. Click the name of an inactive layer to designate it as the active layer.

Clicking the empty square to the left of the name of an inactive layer links that layer to the active layer so that both layers can be moved together - click again to unlink. Linked layers are shown with a chain symbol like this: 

To change the order of layers simply drag the layers' names into the desired position within the layers palette. 

For more help with layers, use the Photoshop help system (Help>Contents>Using Layers)

Do you remember working on a photo of the Luxor Casino in Las Vegas? Let's use our new knowledge of layers to give the photo a more dramatic sky. Here is the original photo again, for you to copy to you personal folder (you may need to change its name if the name clashes with an existing file).

Now right-click HERE to download a dramatic high-resolution photo of a cloudy sky. I photographed this unusual cloud formation from Mougins and made it more sinister by increasing the contrast in Photoshop - I am giving you this photo in high resolution so that you can decide which part of the sky you want to use.

Open both the luxor.jpg picture and the sky.jpg picture in Photoshop, in separate windows. Do you think it would be better to now add the sky to the statue photo or the statue to the sky photo? I think you should add the sky to the existing statue photo since the sky photo is much larger and therefore if you add the statue to the sky it will be too small. So we will copy the sky picture, create a new layer in the statue picture and paste the sky into the new layer.

Make the sky picture active by clicking on it, then use one of these 3 ways to copy the sky image into the statue picture:

1. Select the whole sky picture with Select>All or Ctrl-A and then copy with Ctrl-C. Next, add a new layer to the statue picture using one of the 3 techniques described above and then, while the new layer is active, paste the sky image into it with Ctrl-V.
2. With the source image window active, drag the layer’s name from the Layers palette into the destination image.
3. Use the move tool to drag the layer from the source image to the destination image.

We've finished with the sky picture window, so you can close it now. The sky image is much larger than the canvas, so you can only see a part of it - select the move tool and try moving the sky image - choose the part of the sky you want to use. The sky image is completely obscuring the statue at the moment because the opacity of the sky layer is 100% - try temporarily reducing the opacity level to see how the statue shows through, and then set the opacity back to 100%.

Now we would like to move the statue layer on top of the sky layer - try dragging the statue layer up or the sky layer down in the layer palette. It's impossible! This is because the background image is not really a layer just yet. Convert the background into a layer by double-clicking Background in the layers palette and then typing in the name 'statue' for the layer. Now that the background has been converted into a layer you will be able to drag it above the sky layer.

Now make sure the statue layer is active by clicking its name and then use the magic wand tool to select the whole sky just as you did in the magic wand lesson. Once the sky around the statue has been selected, delete it by pressing the Delete key on the keyboard. This part of the image is now transparent, and lets us see the underlying layer, the alternate sky.

Deselect the selected area with Ctrl-D and boost the brightness of the statue using the layer control or the curve control, just as you did in the previous lesson. You needn't worry about affecting the sky image in the other layer because only the active layer, the 'statue layer' is affected by your changes.

Does that palm tree bother you? If you'd like to get rid of it then try zooming in a few times (Ctrl-Space-Click) and then use the eraser tool to remove it. Where the tree is erased, the sky underneath will be revealed, so it should look fine. Alternatively, you could use the lasso tool to select the tree, being careful not to select the statue. Press delete to delete the selection, then Ctrl-D to deselect the selected area. 

Your picture is now finished but before you can save it as a jpeg image you will need to flatten the two layers into one either by choosing Flatten Image from either the Layer menu or the drop-down menu that appears when you click the triangle in the layers palette.

When you are working with layers, try reducing the opacity of some of the upper layers for some interesting effects - this is easy to do using the Layers palette. Note that 'opacity' is simply the opposite of 'transparency' so 'decreasing the opacity' means 'increasing the transparency'.