This lecture introduces the nextnano software, a Schrödinger-Poisson solver for simulating complex nanostructures. It covers the input structure, material doping, and self-consistent solutions for Poisson, Drift-Diffusion, and Schrödinger Equations. The tutorial includes code examples and details on solving the Poisson equation to obtain charge density distribution and potential. It also explains the initialization, determination of potential, and visualization of output in nextnano.