Setup of a 3D Elmer/Ice simulation explained along the example of a small Alpine glacier (Tete Rousse, Mt. Blanc massif). This lecture contains the setup of a simulation using digital elevation models and introducing the steps to inquire stress fields with and without a water-filled cavity underneath this glacier. This is a record of a webinar held by Olivier Gagliardini during the Elmer/Ice course in November 2020.