Align or Center Multiple Layers?

In the Layers panel, click on the first layer you want to center (or align), press-and-hold the Command (PC: Ctrl) key, and then click on any other layers you also want to center or align to select them, as well (I often align things to the document by choosing the Background layer first, then I Command-click on any other layers I want centered). Now press V to get to the Move tool, then go up to the Options Bar, and you’ll see two sections of alignment icons (just to the right of Show Transform Controls). The icons give you a tiny preview of what each does. In the first section, the second icon centers vertically, and the fifth icon centers your selected layers horizontally. The other icons align the objects on your selected layers to the left or right, or the top or bottom. The second set of icons are for distributing the items on your layers (controlling the space between them equally).