When you're first starting out with artificial lighting, it can feel a bit like trying to speak French in Russian. In between the modifiers, the types of light, and their placement, each setup is a puzzle. This helpful video will describe the main types of lights you'll have in a studio setup and how they relate to each other.
Coming to you from Adorama, this awesome video will walk you through a standard studio light setup, showing how a key light, fill light, hair light, and background light all come together to make a complete portrait setup, as well as how they're typically set in relation to one another. While you certainly don't need four lights to get up and running when you're first starting out (and many photographers make entire careers out of using less), it's important to understand the purpose of the presence, placement, and power of each light, as they do more than just illuminate the subject, adding texture and dimensionality, separating them from the background, and contouring their face. Even if you don't end up using four lights (or more), you can understand which you want to use in each situation.
[via No Film School]