In the Layers panel, select the layer containing the text to which you want to add a drop shadow. Click the Layer Style button at the bottom of the Layers panel and choose Drop Shadow from the list that appears. If possible, position the Layer Style dialog box so that you can see the layer and its drop shadow. Adjust the settings to your liking. You can change various aspects of the shadow, including the way it blends with the layers below it, its opacity (how much the underlying layers show through), the angle of the light, and its distance from the text or object. When you’re satisfied with the drop shadow, click OK.
I hope that helps some. I think you'll have to play with it a bit to get exactly what you want, but this should be a good start.