Hi Andrea,
It depends on your environment and how do you want to integrate the human task module to your application.
You can embed it inside your app adding the jbpm-human-task-core dependency to your project.
You can start a new stand alone instance with the one provided inside the installer -> task-service with the ant goal provided inside the build.xml file
Or you can deploy the jbpm-human-task.war into an application server which will start a standalone version of the human task service inside the container.
Cheers