So far educational adaptive technologies have proven their effectiveness only in small-scale lab courses, thus they still wait for being released to the large community of educators. Among the reasons, there is the difficult task of designing and authoring an interactive adaptive course, especially for non-technical group of educators. In this paper we present VIDET, a visual authoring tool for designing web-based adaptive courses with the ADLEGO adaptive engine. The authoring tool is tailored to the community of non-technical instructors. It is pedagogic-neutral, allowing to define several different instructional strategies. The VIDET tool was implemented as a prototype in Macromedia Flash. Some results from a summative evaluation are available: the tool is effective at reducing the instructor's burden for creating structured adaptive courses. The basic set of adaptive techniques available is complete enough to support several different application scenarios. (Contains 4 tables and 9 figures.)