Motion comics, a digital animation format that enhances comic book narratives, have wide applications in storytelling, education, and advertising. However, their creation poses significant challenges for amateur creators, primarily due to the need for specialized skills and complex workflows. To address these issues, we conducted an exploratory survey (N=58) to understand the challenges associated with creating motion comics, and an expert interview (N=4) to identify a typical workflow for creation. We further analyzed $95$ online motion comics to gain insights into the design space of character and object actions. Based on our findings, we proposed DancingBoard, an integrated authoring tool designed to simplify the creation process. This tool features a user-friendly interface and a guided workflow, providing comprehensive support throughout each step of the creation process. A user study involving 23 creators showed that, compared to professional tools, DancingBoard is easily comprehensible and provides improved guidance and support, requiring less effort from users. Additionally, a separate study with $18$ audience members confirmed the tool's effectiveness in conveying the story to its viewers.