Amy's rant- Or just set the daggone white balance before you shoot and get the exposure right! It's too blue and underexposed. No pricey photoshop actions needed. But the tutorial is quite nice, seriously :) FREE Photoshop Tutorials
These different types of lighting create different gradients and colours of light giving an image more meaning and depth. The way the light is enables the image to be more interesting and direct to what you want for your shoot.