The proliferation of controllable grid-edge resources and the deployment of advanced sensing and control technologies in electric power distribution systems calls for coordinated management of the grid�s resources. This has led to a growing interest in academia and industry alike on optimization methods for the large-scale unbalanced power distribution systems for improved operational efficiency and resilience. This tutorial aims to introduce the state-of-the-art optimization methods applied to unbalanced power distribution systems and their use cases for distribution systems applications. We will start with a discussion on the different models for formulating the distribution optimal power flow (OPF) problem and discuss their trade-offs. We will include hands-on training on modeling the optimization problem using OpenDSS and Matlab/Python for the IEEE test systems. Finally, our industry partner, Opus One Solutions (leader in power systems optimization), will present example application of coordinating grid-edge resources for bulk-energy market using their distribution system Optimization Engine.