I am new to Photoshop trying to design a web page and I was wondering is there any way to assign a "z-index" like feature from CSS to a layer to control overlapping between my images?
To control stacking, you reorder layers in the Layer Panel. (
Window > Layers) Simply click and drag a layer to move it above or below other layers in the panel.
There are also a number of commands to Arrange layers in the
Layer Menu item which also have associated shortcuts you can use.
Reviewing the general help files or starting with some basic Photoshop tutorials found via Google may be of great benefit.