Select Layers in Photoshop CS5
Select the layer you plan to work on by clicking the layer name in the Layers panel. Adobe Photoshop Creative Suite 5 represents a selected layer by simply highlighting the layer in the Layers panel. The indicator paintbrush icon is gone in this version.
When you start working with layers, you may move or adjust pixels, only to discover that you accidentally edited pixels on the wrong layer. Here are some tips to help you select the correct layer:
Select the Move tool and then right-click (Windows) or Control-click (Mac) to see a contextual menu listing all layers that have pixel data at the point you clicked and to choose the layer you want to work with.
Get in the habit of holding down the Ctrl (Windows) or Command (Mac) key while using the Move tool and when selecting layers. This technique temporarily turns on the Auto Select feature, which automatically selects the topmost visible layer that contains the pixel data you clicked.
Press Alt+[ (Windows) or Option+[ (Mac) to select the next layer down from the selected layer in the stacking order.
Press Alt+] (Windows) or Option+] (Mac) to select the next layer up from the selected layer in the stacking order.