It is desirable to provide information adapted to users' needs, whether for learning, working or entertaining. However, developing adaptive systems is not an easy task. In developing discourse-based adaptive systems, one difficulty is that the expertise required to write the discourse operators is complex. In this paper, we present a graphical authoring tool, Constructor, that supports document designers in defining the texts to be generated. Constructor allows people knowledgeable about the application domain to author discourse operators. We also hope that it affords a more intuitive visual way to define documents as compared to the currently laborious encoding of discourse operators. We expect that modifying and creating new document specifications becomes an easier task with Constructor. To test our approach and gain understanding of how to support further the authoring process, we have started user studies. We briefly describe here our initial experiment.