I will try to give a quick introduction (which is everything I can do) to all this program of scattering amplitudes, trying to say a few things about spinor-helicity variables and the BCFW construction. I suppose that this will take the whole time, but if we have some space after this, one can go deeper through two main paths, one being more theoretically oriented seeing how the dual and twistor variables help us to uncover a hidden structure of N=4 and the other perhaps more practical and see how one can attack loop computations with unitarity cuts.