This tutorial will show how to use available Modelica libraries and the Dymola Multi-Engineering Modeling and Simulation environment to solve design problems. The design problems include modeling, validation with measured data, controller design and optimizations. Models will be built up from available standard library component models by graphical composition. An overview of available model libraries will be given. The power of the Modelica language will be summarized, including matrix equations and mixed continuous/discrete models. The Modelica scripting language will be introduced and used for plotting, comparison of data, parameter sweeping, analysing linearized models, etc. The Dymola environment will be used by the participants to solve a small set of problems on their notebook computer (a time-limited license of Dymola will be provided).