Creating a new project or adding files to an existing project
A project can be thought of as a container for all files related to a particular mashup. All files needed to run the mashup are grouped with the project which has the extension .manifest.
When you create a new project, you provide high-level information including project name and author, a description and a version level.
You do not have to create a project before you create the XAML files that will be associated with it. You can assign XAML files to a project at any time.