In this Journal Club, I will discuss a way to construct U(1) and U(1)^n Chern-Simons (CS) Theories. I will start by introducing the main tool that will help us in this construction, the Deligne-Beilinson Cohomology. Then I will proceed by constructing the U(1) CS and BF theories. I will then show how they relate to a different type of invariants called the Reshetikhin-Turaev invariants. And finally, I will perform the equivalent construction for the U(1)^n case.