Buried deep inside the Layer Style dialog box are two slider bars, This Layer and Underlying Layer, that let you blend pixels according to their brightness. Despite their prosaic names, these sliders rank among the most powerful features in all of Photoshop.
Are you new to Photoshop? Have you been trying to teach yourself the basics of Photoshop but have found the amount of amount of educational material available on the net a bit overwhelming?
Here's a tutorial that will help you get over that impression and let you create stunning images!