open Layers palette

Open Layers Palette:

Window > Layers (or F7)

new layer

New layer is always placed above currently selected layer.

There are few ways to create a New (blank) layer:

• Layer > New > Layer
• Layers palette: "Create New Layer" button
• Shift + Ctrl + N

Layer visibility

Everything you do to an image happens only on the selected layer - painting, drawing, adjustments, transformations, etc.

Selected layer is the one that is highlighted in the layers palette.

Once you add something to a layer - it shows in a thumbnail of the Layers palette.

You can hide a layer by clicking on an eye icon.

Click on the "eye" again to view the layer.

delete layer

You can permanently delete a layer by:

• Selecting it
• Dragging it to the "trash can" icon at the bottom of the palette.
  
  
• You can also delete a layer by just clicking on the "trash can" icon (without dragging), but you will need to confirm the deletion

Type (text) layer

Type layer is created automatically when you start using the Type tool.

Type layer has a "T" symbol in the thumbnail area.

With Type layer selected you can move the text around, apply special effects, change font, size, color, etc.

The name of your Type layer reflects the text that you typed.

If you change the text - the name will automatically adjust to the change.

dragging (adding) layers

To combine multiple images (files) in one project:

• Determine which file is going to be your "main" image.
• Have all files open in PS
• Grab the secondary file by the tab at the top of the image window and drag it off the tab group bar
• Select Move tool
• Click and drag the secondary image into your main image window.

A new layer will be automatically created with a default name (Layer 1, Layer 2, etc.)

blend modes

Working with blend modes is almost always an experimental process. Because it’s nearly impossible to predict the results.

A layer’s blending mode determines how its pixels blend with underlying pixels in the image.

Try them all to see the effects.

transparency (opacity)

You can change transparency (opacity) of each layer.

Just go to the layers palette and move the slider or type in the numerical value.

changing layer order

Changing layers order is very simple - just drag a selected layer and drop it where you want it to be moved.

background layer

Background layer is the initial layer that all .JPG images are opened on. It has a few restrictions to prevent you from accidentally moving or editing it.

Background layer (like .JPGs) does not support transparency.

To convert a background layer into a regular layer - all you need is to rename it (by double-clicking on the layer).

layer groups

Layer groups are like file folders - they are a great way to organize your layers.

To create a Layer Group:

• Select the top layer of the layer group
• Click on the folder button in the Layers palette - a folder will appear above the selected layer
• Drag that selected layer into the folder
• Drag the next layer into the group

Layers that are part of a Layer Group are displayed in the Layers palette with their thumbnails being aligned under the folder symbol.

You can always drag a layer out of the layer Group.

You can compress the view of the Layer Group to maximize space in the Layers palette.

other features

Adding an adjustment layer.

Adjustment Layer allows you to apply changes to a layer (or multiple layers) without permanently affecting the layers' pixels.

At any time you can delete the Adjustment layer and discard all changes (contrast, color balance, etc.).

Layer mask

A layer mask in Photoshop is used to control a layer's transparency.

It's great if you wish to reveal or hide portions of a layer using a mask. 

Layer effects.

Layer effects (styles) can be edited or removed later in the Appearance palette.

Link layers to move, edit, and copy them without merging. 

Linked layers stay discrete, meaning you could edit them separately if you wanted. However, every time you click on one linked layer, you automatically adjust the layer(s) it is linked to as well.

This is a good way to make large changes to many layers without having to merge.

(from http://www.wikihow.com/)

erase on a layer

Every layer (except background) can be erased to transparency.

Grey&white checkerboard in layer's thumbnail represents the transparent areas.

edit Type layer

You can edit the text on a Type layer at any time. Select the Type layer first.

To change the text: use Type tool

To change font, size, color, and other font options - use Character or Paragraph palette.

layer style

Photoshop provides a variety of effects—such as shadows, glows, and bevels—that change the appearance of a layer’s contents in a non-distructive way.

Layer effects are linked to the layer contents. When you move or edit the contents of the layer, the same effects are applied to the modified contents. 

A layer style is one or more effects applied to a layer or layer group. 

(from https://helpx.adobe.com)

Layers, that have a style applied to them - have an "fx" symbol.

You can delete the style at any time - restoring the original layer view.