It’s a highly specialized framework for Real Time Web Applications; it’s not a general purpose tool for web pages and web sites. Developers can focus on their projects and don’t worry about HTML, state management, backend services, callbacks, ajax panels, synchronization, DOM, CSS, JavaScript, security, authentication, concurrency…
Visual Studio will create the project template and open the first window in design mode. You can select one of several project templates and add new project items such as pages, custom controls, desktop controls, extensions, etc.