Abstract: The aim of these seminars is to explain the graded algebraic structures, free resolutions of graded rings and modules, Betti numbers, Hilbert Function and Hilbert series with illustrating examples. This is lecture three of this series, I will be discussing about truncated complexes, homomorsphism of complexes and exact sequences. At the end, I will discuss the construction of graded free resolutions and graded betti numbers with various examples. It will provide a glimpse on some exciting directions in which commutative algebraists are working.