If you look in your layers palette, you will notice a drop-down box in its top left corner that usually says "normal".
Well, you can change that! In Photoshop you can choose between dozens of different Blend Modes to change how a particular layer should affect the underlying layers.
Blend modes are incredibly useful, but can be a bit confusing.
To help you in understanding how they work and how they are categorized, I invite you to explore the graph to the left and experiment with different blend modes on your own.