To begin learning how to use Photoshop layers, the "Layers" palette is a good place to start. From this window, users access most of the features available when working with layers. To open the palette, click "Window" on the Photoshop menu bar and then choose "Layers" from the available options. As an alternative, the "Layers" palette can be opened by pressing the <F7> key on your keyboard.
From here you can add layers to your composition, add layer effects, create masks, add fills and adjustments, sort layers into groups, delete layers, and determine whether or not a layer is visible. You can get additional options by clicking the additional options icon at the top right of the window to access most of these and other options.
The different layers that can be added to a composition include Image layers, Effect layers, and Type layers. The background layer is the layer created when a new Photoshop document is created.
Layer features are found along the top of the window and include options to lock transparent pixels, lock image pixels, lock positions,and lock all. A drop down box is found at the upper left section of the window that gives you blending options.
Sliders for opacity and fill are found at the top right of the "Layers" window.
In addition to the "Layers" palette, most options for layers in Adobe Photoshop can be accessed by clicking "Layer" on the main menu and selecting options from that menu.
Image Credits: Screenshots taken by Bruce Tyson