This paper is focused on the design, development and implementation of self-test module and its question units. First, several general considerations in designing the self-test module for a web course are introduced and discussed. The factors that should be considered include the interface, the exercise problem as well as the hint and explanatory answer. Then, multiple real techniques in implementing such a module for a special web course about image processing and analysis are presented. The functions realized contain multiple selection of response code, practical hint or cue, explanatory answer as well as statistic of score. Finally, some examples of resulting modules are illustrated to provide an overview of the module and several bright points of design strategy. The generalization of the approach is also discussed.