In these tutorial talks we will review the available theoretical approaches to study energy transport and thermopower in nano-scale systems,focusing mainly on Molecular junctions.We will begin by reviewing the basic thermodynamic quantities of interest(that is currents and linear response coefficients).We will then review three central approaches: the(essentially classical)rate equations,the non-equilibrium Greens function approach,and the open quantum systems Lindblad approach.For each of these approaches,examples for calculations will be shown,and the advantages(and disadvantages)of each method will be discussed.