There is a learning curve to climb to get to an efficient modeling environment. These tutorials are intended to get you up the curve.
Here is a summary of what you will need to get started.
First, you will need a working copy of the OpenModelica equation solving environment. Versions are available for both Windows and popular Linux disttrsbution. Installation will be painless (in my experience), although the size of the download is quite large (a fast Internet connection is desirable).
Second, you will need some (a few, not all, I recommend starting with the five essential tools) of the modeltools tools. Downloads are located in the user's guides.
Third, a model in the modeltools environment is called a project. A project consists of a model description which is an XML document comprised of a single file or many files. In addition to the XML model specification document, there are additional files and folders that the model tools use during a simulation session. The names and organization of these files and folders is significant, thereby reducing administrative workload to near zero.
Fourth, you will see how to navigate among projects. There is a modeltools tool for this (modelproject). Once the name and location of the current project's root folder has been specified, all of the model tools know where to visit without further setup.