here are a couple of handy tricks for working with layers.

this image is going to be deep-etched. we first have to turn the background layer into an active layer (notice the lock in the layers panel) :

to achieve that, just double-click the layer. this will open a dialog box asking you to name the layer. if you’re happy to just use the default name (Layer 0) — hold down your option key before you double-click to bypass the dialog. but in this case a different name was applied :

now, we’re only a couple of sentences in and it’s already time for a rant …
if you are going to deep-etch an image, DO NOT DESTROY PIXELS. there is absolutely no good reason for permanently erasing a background. you should always use a mask instead. you can read more about making masks here. masks are created with the mask button at the bottom of the layers panel :

if you click the new layer button you’ll get a new layer above the currently selected layer or, if no layers are selected, at the top of the layer stack. but if you want the new layer beneath the current one, or at the bottom of the stack, hold the command key as you click :

to name a new layer as you create it, just hold the option key as you click the new layer button. this also works if you are duplicating an existing layer by dragging it onto the new layer button (but not if you are duplicating with the right-click method).

now we need to add a logo from another file. first you need the new file in a separate window in front of your working file (so that you can see both files) then just click and drag the layer you want from the new file’s layers panel into your working file. you can also do this with multiple layers (just command-click to select multiple layers) :

to make things a little easier, hold the shift key as you click and drag. this will place the new layers dead centre :

to rename an existing layer, double-click on the name in the layers panel.