Here’s something you might want to read and bookmark for future reference. Photographer Robert Thomas has written up an in-depth article explaining what the different Photoshop blending modes are and how they actually work:
Working with blend modes is almost always an experimental process. Because it’s nearly impossible to predict the results, you always seem to end up experimenting with different modes and Fill Opacities until you get the results you’re looking for.
In this article I’m going to give you a high-level view of what the various blend modes do, and then I’ll dig deeper into the nuts and bolts of the blend modes by explaining some of the math involved, and their interrelationships with each other. I’m not going to “show” you how the blend modes work—I’m going to “explain” how they work. By the time you finish reading this article, you should have a better idea of how to use blend modes and where to begin your “experimentation,” which in turn should reduce the time it takes to achieve the results you’re looking for.