Dipolar interactions between electron spins affect magnetic properties of matter on microscopic and macroscopic scales. An understanding of dynamical quantum magnetism enables researchers to explain behaviors of magnetic materials, which lead to a development of technology related to condensed matter physics. However, there are still open questions about how a non-equilibrium spin system evolve in the presence of disorder and long-range interactions. The description of this evolution is generally difficult to achieve because of the complexity in the preparation of large samples with fully control in states and experimental conditions. In this work, we used Rydberg-spin systems to study non-equilibrium many-body spin dynamics. With an ability to fully control the spin state and spin interactions, the work uncovered the relaxation dynamics and reveal the evolution of the spin systems. The techniques implemented in this work including state-selective detection as well as precise microwave control for spin manipulation can be advantageous for other research groups that utilize spin systems to study magnetism as well as condensed matter physicists.