The Project list is a screen that shows all registered Projects in Astah Share. Projects are what you first need to create when you start Astah Share, then you can add .astah files to the Project to get them on Astah Share.
In Astah Share, Project is a top level concept and a folder that holds multiple project files(.astah). Project is essential to use Astah Share. For how to manage Projects (Create, Modify and delete them etc), please refer to Project Management.
There are two ways to open a project.