Hi,
In order to create new users you need to specify them in two places,
1) the first is in the OrganizationalEntity table of the database (either by inserting the user directly to the database or via the LoadUsers.mvel used by the task service found in the jbpm5 installation jbpm-installer\task-service\src\org\jbpm and jbpm-installer\task-service\resources\org\jbpm )
2)specify the users in the installation of jboss i.e. jbpm-installer\jboss-5.1.0.GA\server\default\conf users.properties roles.properties