[Tamlin]

You don't really need a tutorial to get your head round Layer Styles - the best way to learn about them is to experiment.
Just create a new image, create a new layer, then put something on it - add some text or draw a shape with the Shape tool. Next, click on the Add a layer style button at the bottom of the Layers palette and select one that you want to try out. The Layer Style dialog will open - make sure that Preview is selected, then move the dialog so that you can see the effects on your object. Play around with the settings. Click on one of the other Layer Styles listed in the left-hand pane of the dialog, and observe the effect of changing its settings. Try combining two or more Layer Styles (just click in the check boxes to enable them, or clear the check boxes to turn them off). Try applying a ready-made Layer Style, then open the Layer Styles dialog (double-click on the f icon) and examine how the style has been constructed.