Effective tutorial systems can help promote products by reducing barriers of learning new applications. With dynamic web applications becoming as complex as desktop programs, there is a growing need for online tutorial/help systems. For visually impaired users the key limitations of traditional help systems are 1) poor access to help content with assistive technology, and 2) frequent reliance on videos/images to identify parts of web applications and demonstrate functionality. In this paper, we present a new interaction model, targeted towards screen-reader users, that describes how to embed an interactive tutorial within a web application. The interaction model is demonstrated within a system called DTorial, a fully functional dynamic audio-based tutorial with embedded content. While remaining within the web application, users can rapidly access any tutorial content, injected inline near relevant application controls, allowing them to quickly apply what they just heard to the application itself, without ever losing their position or having to shift windows. The model and implementation are grounded in sighted user help-systems literature and an analysis of screen-reader and Web-Application interactions. Lessons learned from the incremental design and evaluations indicate that providing visually impaired users with dynamic, embedded, interactive audio-based tutorial systems can reduce the barriers to new Web-Applications.