Create a project with Modelio. You can check the Java project option so the project will be automatically configured for Java development (It requires that the Java Designer module is available in the Modules catalog).
If you didn't download the Java Designer module, please download it, add it to the Modules catalog then add it to your project.(How to manage the Modelio modules catalog - How to manage modules in a project)
The Java Designer module should appear in the Project's modules.
Before starting to reverse sources, you must configure the libraries used by the application to be reversed. Right-click on the project's root package and select "Java Designer/Configuration/Edit accessible classes".
Right-click on the project's root package and select "Java Designer/Reverse/Reverse Java application from sources" (You also can use "Reverse Java binaries" which don't reverse the source code).
In the first window, enter the source path of the application and select the elements to reverse.
In the next window, you can ignore some libraries.
In the final window, you can specifiy the classpath of the application to be reversed. You can leave it empty.
Click on the Reverse button and the process starts.
A window will appear with some information about the reverse result. Close it and you will see that the model has been updated.