Groundwater modelling can be done on multiple temporal and spatial scales, from a laboratory setup to a complete basin, from steady-state to thousands of years. Each modelling requirement has a specific discretization and boundary condition setup. This tutorial cover a regional groundwater modelling example on a andean basin on steady state conditions, the tutorial covers the whole set of modelling steps as grid generation and elevation import as well as the model simulation and result evaluation. Numerical modelling was done in open source software as MODFLOW with Model Muse, both developed by the USGS.