In order to systematize development, software companies define their organizational processes. The process engineer is in charge of this activity. Tailoring software processes is an activity that allows project managers to adapt organizational software processes to the needs of particular projects. Modeldriven engineering (MDE) has been applied with that purpose using process model tailoring transformations. Although this approach is technically feasible, there are still factors that jeopardize its usage in industry. First, current transformation languages and tools are not simple for defining and applying tailoring transformations. Second, the potential users-process engineers and project managers-do not usually have the required knowledge for writing transformations. Trying to deal with these usability challenges, this paper proposes an MDE-based tool that allows defining the models for the organizational software process and the organizational context, as well as tailoring rules using a usable user interface, so that the project manager just requires to define the project context of the particular project in order to automatically obtain the tailored process. This usable interface hides the complexities of the tool backend built as a megamodel, requiring from the process engineer and the project manager only knowledge about project characteristics and how they affect tailoring. We report our experience of applying the tool in a real-world software process and we outline this experience in http://www.dcc.uchile.cl/gems/docs/DemoMODELS2015.pdf.