Today's generation often seeks help from each other in online environments; however, only a few have investigated the role of Internet technologies and the nature of online help-seeking behaviour in collaborative learning environments. This paper presents an educational design research project that examines college students' online help-seeking behaviour. The context was a large-enrollment science course that implemented a form of blended instruction - the flipped classroom. This paper proposes design guidelines for promoting help-seeking and discusses the application of these principles in the design of a web-based help-seeking tool (EchoLu). The study involved three iterations of implementation to continuously refine the web-based tool, and therefore to better address the help-seeking needs of students in the context. The revisions incorporated between iterations helped improve the embodiment of design principles and led to positive changes in students' perceptions. The triangulated data revealed students' interest in information-seeking as an additional form of help-seeking. The results of this study provide insight into the theories that informed the design of EchoLu and the design principles themselves. A new model illustrating processes involved in online help-seeking is discussed, and an emergent principle for online help-seeking is suggested.